Merge commit from fork

* Inject DenyList from config to `StartCommands()`

* Implementation draft

* Move address checker to separate package

* Migrate usages of actions.AddressChecker to denylist.AddressChecker

* Rename denylist package files

* Pass []denylist.AddressChecker to StartCommand

* Add DenyList to defaults.yaml and add custom config parser

* net: add HostnameToIPList function

* denylist: Add IsHostBlocked()

* actions: use denylist.IsHostBlocked()

* command: Inject ip lookup function + extend add target validationt test

* command: Unexport ChangeTarget.IsValid()

* command: Add denyList check on ChangeTarget validation

* command: Export ActionsV2DenyList and IPLookupFunction params

* Lint fix

* Check denylist during action execution

* Fix integration tests

* Apply suggestions

* Add `mapstructure.StringToSliceHookFunc()` to decode `HTTPConfigDecodeHook`

apps/api/test-integration-api.yaml

@@ -76,6 +76,9 @@ LogStore:
     Stdout:
       Enabled: true
 
+Executions:
+  DenyList: # ZITADEL_EXECUTIONS_DENYLIST (comma separated list)
+
 Projections:
   HandleActiveInstances: 30m
   RequeueEvery: 20s

cmd/defaults.yaml

@@ -574,6 +574,14 @@ Executions:
   TransactionDuration: 10s # ZITADEL_EXECUTIONS_TRANSACTIONDURATION
   # Automatically cancel the notification if it cannot be handled within a specific time
   MaxTtl: 5m  # ZITADEL_EXECUTIONS_MAXTTL
+  # List of domains and IPs that are not valid execution target's endpoints
+  # Wildcard sub domains are currently unsupported
+  DenyList: # ZITADEL_EXECUTIONS_DENYLIST (comma separated list)
+    - localhost
+    - "127.0.0.0/8"
+    - "::1"
+    - "0.0.0.0"
+    - "::"
 
 Auth:
   # See Projections.BulkLimit

cmd/mirror/config.go

@@ -18,6 +18,7 @@ import (
 	"github.com/zitadel/zitadel/internal/command"
 	"github.com/zitadel/zitadel/internal/config/hook"
 	"github.com/zitadel/zitadel/internal/database"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/id"
 )
@@ -100,6 +101,7 @@ func newConfig(v *viper.Viper, config any) error {
 			mapstructure.StringToSliceHookFunc(","),
 			database.DecodeHook(true),
 			actions.HTTPConfigDecodeHook,
+			denylist.DenyListDecodeHook,
 			hook.EnumHookFunc(internal_authz.MemberTypeString),
 			mapstructure.TextUnmarshallerHookFunc(),
 		)),

cmd/mirror/projections.go

@@ -34,6 +34,7 @@ import (
 	"github.com/zitadel/zitadel/internal/config/systemdefaults"
 	crypto_db "github.com/zitadel/zitadel/internal/crypto/database"
 	"github.com/zitadel/zitadel/internal/database"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore"
 	old_es "github.com/zitadel/zitadel/internal/eventstore/repository/sql"
@@ -215,6 +216,7 @@ func projections(
 		config.OIDC.DefaultRefreshTokenIdleExpiration,
 		config.DefaultInstance.SecretGenerators,
 		config.Login.DefaultPaths,
+		[]denylist.AddressChecker{},
 	)
 	logging.OnError(ctx, err).Fatal("unable to start commands")
 

cmd/setup/03.go

@@ -16,6 +16,7 @@ import (
 	"github.com/zitadel/zitadel/internal/crypto"
 	crypto_db "github.com/zitadel/zitadel/internal/crypto/database"
 	"github.com/zitadel/zitadel/internal/database"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore"
 )
@@ -96,6 +97,7 @@ func (mig *FirstInstance) Execute(ctx context.Context, _ eventstore.Event) error
 		0,
 		nil,
 		mig.defaultPaths,
+		[]denylist.AddressChecker{},
 	)
 	if err != nil {
 		return err

cmd/setup/config.go

@@ -26,6 +26,7 @@ import (
 	"github.com/zitadel/zitadel/internal/config/hook"
 	"github.com/zitadel/zitadel/internal/config/systemdefaults"
 	"github.com/zitadel/zitadel/internal/database"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore"
 	"github.com/zitadel/zitadel/internal/execution"
@@ -81,6 +82,7 @@ func NewConfig(cmd *cobra.Command, v *viper.Viper) (*Config, instrumentation.Shu
 			hooks.MapTypeStringDecode[string, *authz.SystemAPIUser],
 			hooks.MapHTTPHeaderStringDecode,
 			database.DecodeHook(false),
+			denylist.DenyListDecodeHook,
 			actions.HTTPConfigDecodeHook,
 			hook.EnumHookFunc(authz.MemberTypeString),
 			hook.Base64ToBytesHookFunc(),

cmd/setup/config_change.go

@@ -7,6 +7,7 @@ import (
 	"github.com/zitadel/zitadel/internal/cache/connector"
 	"github.com/zitadel/zitadel/internal/command"
 	"github.com/zitadel/zitadel/internal/config/systemdefaults"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/eventstore"
 )
 
@@ -60,6 +61,7 @@ func (mig *externalConfigChange) Execute(ctx context.Context, _ eventstore.Event
 		0,
 		nil,
 		&login.DefaultPaths{},
+		[]denylist.AddressChecker{},
 	)
 
 	if err != nil {

cmd/setup/setup.go

@@ -575,6 +575,7 @@ func startCommandsQueries(
 		config.OIDC.DefaultRefreshTokenIdleExpiration,
 		config.DefaultInstance.SecretGenerators,
 		config.Login.DefaultPaths,
+		config.Executions.DenyList,
 	)
 	logging.OnError(ctx, err).Fatal("unable to start commands")
 

cmd/start/config.go

@@ -30,6 +30,7 @@ import (
 	"github.com/zitadel/zitadel/internal/config/network"
 	"github.com/zitadel/zitadel/internal/config/systemdefaults"
 	"github.com/zitadel/zitadel/internal/database"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore"
 	"github.com/zitadel/zitadel/internal/execution"
@@ -146,6 +147,7 @@ func readConfig(v *viper.Viper) (*Config, error) {
 			hooks.MapHTTPHeaderStringDecode,
 			database.DecodeHook(false),
 			actions.HTTPConfigDecodeHook,
+			denylist.DenyListDecodeHook,
 			hook.EnumHookFunc(authz.MemberTypeString),
 			hooks.MapTypeStringDecode[domain.Feature, any],
 			hooks.SliceTypeStringDecode[*command.SetQuota],

cmd/start/config_test.go

@@ -14,9 +14,9 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/zitadel/zitadel/internal/actions"
 	"github.com/zitadel/zitadel/internal/api/authz"
 	"github.com/zitadel/zitadel/internal/command"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/feature"
 )
@@ -48,10 +48,10 @@ Log:
   Level: info
 `},
 		want: func(t *testing.T, config *Config) {
-			assert.Equal(t, config.Actions.HTTP.DenyList, []actions.AddressChecker{
-				&actions.HostChecker{Domain: "localhost"},
-				&actions.HostChecker{IP: net.ParseIP("127.0.0.1")},
-				&actions.HostChecker{Domain: "foobar"}})
+			assert.Equal(t, config.Actions.HTTP.DenyList, []denylist.AddressChecker{
+				&denylist.HostChecker{Domain: "localhost"},
+				&denylist.HostChecker{IP: net.ParseIP("127.0.0.1")},
+				&denylist.HostChecker{Domain: "foobar"}})
 		},
 	}, {
 		name: "actions deny list string ok",
@@ -64,10 +64,10 @@ Log:
   Level: info
 `},
 		want: func(t *testing.T, config *Config) {
-			assert.Equal(t, config.Actions.HTTP.DenyList, []actions.AddressChecker{
-				&actions.HostChecker{Domain: "localhost"},
-				&actions.HostChecker{IP: net.ParseIP("127.0.0.1")},
-				&actions.HostChecker{Domain: "foobar"}})
+			assert.Equal(t, config.Actions.HTTP.DenyList, []denylist.AddressChecker{
+				&denylist.HostChecker{Domain: "localhost"},
+				&denylist.HostChecker{IP: net.ParseIP("127.0.0.1")},
+				&denylist.HostChecker{Domain: "foobar"}})
 		},
 	}, {
 		name: "features ok",

cmd/start/start.go

@@ -289,6 +289,7 @@ func startZitadel(ctx context.Context, config *Config, masterKey string, server
 		config.OIDC.DefaultRefreshTokenIdleExpiration,
 		config.DefaultInstance.SecretGenerators,
 		config.Login.DefaultPaths,
+		config.Executions.DenyList,
 	)
 	if err != nil {
 		return fmt.Errorf("cannot start commands: %w", err)
@@ -478,6 +479,7 @@ func startAPIs(
 		keys.Target,
 		translator,
 		config.Instrumentation.Trace.TrustRemoteSpans,
+		config.Executions.DenyList,
 	)
 	if err != nil {
 		return nil, fmt.Errorf("error creating api %w", err)

internal/actions/http_module.go

@@ -7,13 +7,13 @@ import (
 	"io"
 	"net"
 	"net/http"
-	"net/url"
 	"strings"
 	"time"
 
 	"github.com/dop251/goja"
 	"github.com/zitadel/logging"
 
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/zerrors"
 )
 
@@ -179,32 +179,9 @@ func (t *transport) RoundTrip(req *http.Request) (*http.Response, error) {
 	if httpConfig == nil || len(httpConfig.DenyList) == 0 {
 		return http.DefaultTransport.RoundTrip(req)
 	}
-	if err := t.isHostBlocked(httpConfig.DenyList, req.URL); err != nil {
+
+	if err := denylist.IsHostBlocked(httpConfig.DenyList, req.URL, t.lookup); err != nil {
 		return nil, zerrors.ThrowInvalidArgument(err, "ACTIO-N72d0", "host is denied")
 	}
 	return http.DefaultTransport.RoundTrip(req)
 }
-
-func (t *transport) isHostBlocked(denyList []AddressChecker, address *url.URL) error {
-	host := address.Hostname()
-	ip := net.ParseIP(host)
-	ips := []net.IP{ip}
-	// if the hostname is a domain, we need to check resolve the ip(s), since it might be denied
-	if ip == nil {
-		var err error
-		ips, err = t.lookup(host)
-		if err != nil {
-			return zerrors.ThrowInternal(err, "ACTIO-4m9s2", "lookup failed")
-		}
-	}
-	for _, denied := range denyList {
-		if err := denied.IsDenied(ips, host); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-type AddressChecker interface {
-	IsDenied([]net.IP, string) error
-}

internal/actions/http_module_config.go

@@ -1,13 +1,11 @@
 package actions
 
 import (
-	"errors"
-	"fmt"
-	"net"
 	"reflect"
-	"strings"
 
 	"github.com/mitchellh/mapstructure"
+
+	"github.com/zitadel/zitadel/internal/denylist"
 )
 
 func SetHTTPConfig(config *HTTPConfig) {
@@ -17,11 +15,11 @@ func SetHTTPConfig(config *HTTPConfig) {
 var httpConfig *HTTPConfig
 
 type HTTPConfig struct {
-	DenyList []AddressChecker
+	DenyList []denylist.AddressChecker
 }
 
-func HTTPConfigDecodeHook(from, to reflect.Value) (interface{}, error) {
-	if to.Type() != reflect.TypeOf(HTTPConfig{}) {
+func HTTPConfigDecodeHook(from, to reflect.Value) (any, error) {
+	if to.Type() != reflect.TypeFor[HTTPConfig]() {
 		return from.Interface(), nil
 	}
 
@@ -30,7 +28,10 @@ func HTTPConfigDecodeHook(from, to reflect.Value) (interface{}, error) {
 	}{}
 
 	decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
-		DecodeHook:       mapstructure.StringToTimeDurationHookFunc(),
+		DecodeHook: mapstructure.ComposeDecodeHookFunc(
+			mapstructure.StringToTimeDurationHookFunc(),
+			mapstructure.StringToSliceHookFunc(","),
+		),
 		WeaklyTypedInput: true,
 		Result:           &config,
 	})
@@ -43,77 +44,13 @@ func HTTPConfigDecodeHook(from, to reflect.Value) (interface{}, error) {
 	}
 
 	c := HTTPConfig{
-		DenyList: make([]AddressChecker, 0),
+		DenyList: make([]denylist.AddressChecker, 0),
 	}
 
-	for _, unsplit := range config.DenyList {
-		for _, split := range strings.Split(unsplit, ",") {
-			parsed, parseErr := NewHostChecker(split)
-			if parseErr != nil {
-				return nil, parseErr
-			}
-			if parsed != nil {
-				c.DenyList = append(c.DenyList, parsed)
-			}
-		}
+	c.DenyList, err = denylist.ParseDenyList(config.DenyList)
+	if err != nil {
+		return nil, err
 	}
 
 	return c, nil
 }
-
-func NewHostChecker(entry string) (AddressChecker, error) {
-	if entry == "" {
-		return nil, nil
-	}
-	_, network, err := net.ParseCIDR(entry)
-	if err == nil {
-		return &HostChecker{Net: network}, nil
-	}
-	if ip := net.ParseIP(entry); ip != nil {
-		return &HostChecker{IP: ip}, nil
-	}
-	return &HostChecker{Domain: entry}, nil
-}
-
-type HostChecker struct {
-	Net    *net.IPNet
-	IP     net.IP
-	Domain string
-}
-
-type AddressDeniedError struct {
-	deniedBy string
-}
-
-func NewAddressDeniedError(deniedBy string) *AddressDeniedError {
-	return &AddressDeniedError{deniedBy: deniedBy}
-}
-
-func (e *AddressDeniedError) Error() string {
-	return fmt.Sprintf("address is denied by '%s'", e.deniedBy)
-}
-
-func (e *AddressDeniedError) Is(target error) bool {
-	var addressDeniedErr *AddressDeniedError
-	if !errors.As(target, &addressDeniedErr) {
-		return false
-	}
-	return e.deniedBy == addressDeniedErr.deniedBy
-}
-
-func (c *HostChecker) IsDenied(ips []net.IP, address string) error {
-	// if the address matches the domain, no additional checks as needed
-	if c.Domain == address {
-		return NewAddressDeniedError(c.Domain)
-	}
-	// otherwise we need to check on ips (incl. the resolved ips of the host)
-	for _, ip := range ips {
-		if c.Net != nil && c.Net.Contains(ip) {
-			return NewAddressDeniedError(c.Net.String())
-		}
-		if c.IP != nil && c.IP.Equal(ip) {
-			return NewAddressDeniedError(c.IP.String())
-		}
-	}
-	return nil
-}

internal/actions/http_module_test.go

@@ -4,123 +4,16 @@ import (
 	"bytes"
 	"context"
 	"io"
-	"net"
 	"net/http"
 	"net/url"
 	"reflect"
 	"testing"
 
 	"github.com/dop251/goja"
-	"github.com/stretchr/testify/assert"
 
-	"github.com/zitadel/zitadel/internal/logstore"
-	"github.com/zitadel/zitadel/internal/logstore/record"
 	"github.com/zitadel/zitadel/internal/zerrors"
 )
 
-func Test_isHostBlocked(t *testing.T) {
-	SetLogstoreService(logstore.New[*record.ExecutionLog](nil, nil))
-	var denyList = []AddressChecker{
-		mustNewHostChecker(t, "192.168.5.0/24"),
-		mustNewHostChecker(t, "127.0.0.1"),
-		mustNewHostChecker(t, "test.com"),
-	}
-	type fields struct {
-		lookup func(host string) ([]net.IP, error)
-	}
-	type args struct {
-		address *url.URL
-	}
-	tests := []struct {
-		name   string
-		fields fields
-		args   args
-		want   error
-	}{
-		{
-			name: "in range",
-			args: args{
-				address: mustNewURL(t, "https://192.168.5.4/hodor"),
-			},
-			want: NewAddressDeniedError("192.168.5.0/24"),
-		},
-		{
-			name: "exact ip",
-			args: args{
-				address: mustNewURL(t, "http://127.0.0.1:8080/hodor"),
-			},
-			want: NewAddressDeniedError("127.0.0.1"),
-		},
-		{
-			name: "address match",
-			fields: fields{
-				lookup: func(host string) ([]net.IP, error) {
-					return []net.IP{net.ParseIP("194.264.52.4")}, nil
-				},
-			},
-			args: args{
-				address: mustNewURL(t, "https://test.com:42/hodor"),
-			},
-			want: NewAddressDeniedError("test.com"),
-		},
-		{
-			name: "address not match",
-			fields: fields{
-				lookup: func(host string) ([]net.IP, error) {
-					return []net.IP{net.ParseIP("194.264.52.4")}, nil
-				},
-			},
-			args: args{
-				address: mustNewURL(t, "https://test2.com/hodor"),
-			},
-			want: nil,
-		},
-		{
-			name: "looked up ip matches",
-			fields: fields{
-				lookup: func(host string) ([]net.IP, error) {
-					return []net.IP{net.ParseIP("127.0.0.1")}, nil
-				},
-			},
-			args: args{
-				address: mustNewURL(t, "https://test2.com/hodor"),
-			},
-			want: NewAddressDeniedError("127.0.0.1"),
-		},
-		{
-			name: "looked up failure",
-			fields: fields{
-				lookup: func(host string) ([]net.IP, error) {
-					return nil, io.EOF
-				},
-			},
-			args: args{
-				address: mustNewURL(t, "https://test2.com/hodor"),
-			},
-			want: zerrors.ThrowInternal(io.EOF, "ACTIO-4m9s2", "lookup failed"),
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			trans := &transport{
-				lookup: tt.fields.lookup,
-			}
-			got := trans.isHostBlocked(denyList, tt.args.address)
-			assert.ErrorIs(t, got, tt.want)
-		})
-	}
-}
-
-func mustNewHostChecker(t *testing.T, ip string) AddressChecker {
-	t.Helper()
-	checker, err := NewHostChecker(ip)
-	if err != nil {
-		t.Errorf("unable to parse cidr of %q because: %v", ip, err)
-		t.FailNow()
-	}
-	return checker
-}
-
 func mustNewURL(t *testing.T, raw string) *url.URL {
 	u, err := url.Parse(raw)
 	if err != nil {

internal/api/api.go

@@ -26,6 +26,7 @@ import (
 	http_mw "github.com/zitadel/zitadel/internal/api/http/middleware"
 	"github.com/zitadel/zitadel/internal/api/ui/login"
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/i18n"
 	"github.com/zitadel/zitadel/internal/query"
 	"github.com/zitadel/zitadel/internal/telemetry/tracing"
@@ -57,6 +58,7 @@ type API struct {
 	targetEncryptionAlgorithm crypto.EncryptionAlgorithm
 	translator                *i18n.Translator
 	connectOTELInterceptor    *otelconnect.Interceptor
+	actionV2DenyList          []denylist.AddressChecker
 }
 
 func (a *API) ListGrpcServices() []string {
@@ -111,6 +113,7 @@ func New(
 	targetEncryptionAlgorithm crypto.EncryptionAlgorithm,
 	translator *i18n.Translator,
 	trustRemoteSpans bool,
+	deniedIPList []denylist.AddressChecker,
 ) (_ *API, err error) {
 	api := &API{
 		port:                      port,
@@ -126,9 +129,10 @@ func New(
 		connectServices:           make(map[string][]string),
 		targetEncryptionAlgorithm: targetEncryptionAlgorithm,
 		translator:                translator,
+		actionV2DenyList:          deniedIPList,
 	}
 
-	api.grpcServer = server.CreateServer(api.verifier, systemAuthz, authZ, queries, externalDomain, tlsConfig, accessInterceptor.AccessService(), targetEncryptionAlgorithm, api.translator)
+	api.grpcServer = server.CreateServer(api.verifier, systemAuthz, authZ, queries, externalDomain, tlsConfig, accessInterceptor.AccessService(), targetEncryptionAlgorithm, api.translator, deniedIPList)
 	api.grpcGateway, err = server.CreateGateway(ctx, port, hostHeaders, accessInterceptor, tlsConfig)
 	if err != nil {
 		return nil, err
@@ -219,7 +223,7 @@ func (a *API) registerConnectServer(service server.ConnectServer) {
 		connect_middleware.AuthorizationInterceptor(a.verifier, a.systemAuthZ, a.authConfig),
 		connect_middleware.TranslationHandler(),
 		connect_middleware.QuotaExhaustedInterceptor(a.accessInterceptor.AccessService(), system_pb.SystemService_ServiceDesc.ServiceName),
-		connect_middleware.ExecutionHandler(a.targetEncryptionAlgorithm, a.queries.GetActiveSigningWebKey),
+		connect_middleware.ExecutionHandler(a.targetEncryptionAlgorithm, a.queries.GetActiveSigningWebKey, a.actionV2DenyList),
 		connect_middleware.ValidationHandler(),
 		connect_middleware.ServiceHandler(),
 		connect_middleware.ActivityInterceptor(),

internal/api/grpc/action/v2/integration_test/execution_target_test.go

@@ -71,7 +71,7 @@ func TestServer_ExecutionTarget(t *testing.T) {
 
 				// create target for target changes
 				targetCreatedName := integration.TargetName()
-				targetCreatedURL := "https://nonexistent"
+				targetCreatedURL := "https://example.com"
 				targetCreatedPayloadType := action.PayloadType_PAYLOAD_TYPE_JSON
 
 				targetCreated := instance.CreateTarget(ctx, t, targetCreatedName, targetCreatedURL, target_domain.TargetTypeCall, false, targetCreatedPayloadType)
@@ -225,7 +225,7 @@ func TestServer_ExecutionTarget(t *testing.T) {
 
 				// create target for target changes
 				targetCreatedName := integration.TargetName()
-				targetCreatedURL := "https://nonexistent"
+				targetCreatedURL := "https://example.com"
 				targetCreatedPayloadType := action.PayloadType_PAYLOAD_TYPE_JSON
 
 				targetCreated := instance.CreateTarget(ctx, t, targetCreatedName, targetCreatedURL, target_domain.TargetTypeCall, false, targetCreatedPayloadType)

internal/api/grpc/action/v2/integration_test/execution_test.go

@@ -18,7 +18,7 @@ import (
 func TestServer_SetExecution_Request(t *testing.T) {
 	instance := integration.NewInstance(CTX)
 	isolatedIAMOwnerCTX := instance.WithAuthorizationToken(CTX, integration.UserTypeIAMOwner)
-	targetResp := instance.CreateTarget(isolatedIAMOwnerCTX, t, "", "https://notexisting", target_domain.TargetTypeWebhook, false, action.PayloadType_PAYLOAD_TYPE_JSON)
+	targetResp := instance.CreateTarget(isolatedIAMOwnerCTX, t, "", "https://example.com", target_domain.TargetTypeWebhook, false, action.PayloadType_PAYLOAD_TYPE_JSON)
 
 	tests := []struct {
 		name        string
@@ -175,7 +175,7 @@ func assertSetExecutionResponse(t *testing.T, creationDate, setDate time.Time, e
 func TestServer_SetExecution_Response(t *testing.T) {
 	instance := integration.NewInstance(CTX)
 	isolatedIAMOwnerCTX := instance.WithAuthorizationToken(CTX, integration.UserTypeIAMOwner)
-	targetResp := instance.CreateTarget(isolatedIAMOwnerCTX, t, "", "https://notexisting", target_domain.TargetTypeWebhook, false, action.PayloadType_PAYLOAD_TYPE_JSON)
+	targetResp := instance.CreateTarget(isolatedIAMOwnerCTX, t, "", "https://example.com", target_domain.TargetTypeWebhook, false, action.PayloadType_PAYLOAD_TYPE_JSON)
 
 	tests := []struct {
 		name        string
@@ -319,7 +319,7 @@ func TestServer_SetExecution_Response(t *testing.T) {
 func TestServer_SetExecution_Event(t *testing.T) {
 	instance := integration.NewInstance(CTX)
 	isolatedIAMOwnerCTX := instance.WithAuthorizationToken(CTX, integration.UserTypeIAMOwner)
-	targetResp := instance.CreateTarget(isolatedIAMOwnerCTX, t, "", "https://notexisting", target_domain.TargetTypeWebhook, false, action.PayloadType_PAYLOAD_TYPE_JSON)
+	targetResp := instance.CreateTarget(isolatedIAMOwnerCTX, t, "", "https://example.com", target_domain.TargetTypeWebhook, false, action.PayloadType_PAYLOAD_TYPE_JSON)
 
 	tests := []struct {
 		name        string
@@ -482,7 +482,7 @@ func TestServer_SetExecution_Event(t *testing.T) {
 func TestServer_SetExecution_Function(t *testing.T) {
 	instance := integration.NewInstance(CTX)
 	isolatedIAMOwnerCTX := instance.WithAuthorizationToken(CTX, integration.UserTypeIAMOwner)
-	targetResp := instance.CreateTarget(isolatedIAMOwnerCTX, t, "", "https://notexisting", target_domain.TargetTypeWebhook, false, action.PayloadType_PAYLOAD_TYPE_JSON)
+	targetResp := instance.CreateTarget(isolatedIAMOwnerCTX, t, "", "https://example.com", target_domain.TargetTypeWebhook, false, action.PayloadType_PAYLOAD_TYPE_JSON)
 
 	tests := []struct {
 		name        string

internal/api/grpc/action/v2beta/integration_test/execution_target_test.go

@@ -71,7 +71,7 @@ func TestServer_ExecutionTarget(t *testing.T) {
 
 				// create target for target changes
 				targetCreatedName := integration.TargetName()
-				targetCreatedURL := "https://nonexistent"
+				targetCreatedURL := "https://example.com"
 
 				targetCreated := instance.CreateTargetWithoutPayloadType(ctx, t, targetCreatedName, targetCreatedURL, target_domain.TargetTypeCall, false)
 
@@ -221,7 +221,7 @@ func TestServer_ExecutionTarget(t *testing.T) {
 
 				// create target for target changes
 				targetCreatedName := integration.TargetName()
-				targetCreatedURL := "https://nonexistent"
+				targetCreatedURL := "https://example.com"
 
 				targetCreated := instance.CreateTargetWithoutPayloadType(ctx, t, targetCreatedName, targetCreatedURL, target_domain.TargetTypeCall, false)
 

internal/api/grpc/action/v2beta/integration_test/execution_test.go

@@ -18,7 +18,7 @@ import (
 func TestServer_SetExecution_Request(t *testing.T) {
 	instance := integration.NewInstance(CTX)
 	isolatedIAMOwnerCTX := instance.WithAuthorizationToken(CTX, integration.UserTypeIAMOwner)
-	targetResp := instance.CreateTargetWithoutPayloadType(isolatedIAMOwnerCTX, t, "", "https://notexisting", target_domain.TargetTypeWebhook, false)
+	targetResp := instance.CreateTargetWithoutPayloadType(isolatedIAMOwnerCTX, t, "", "https://example.com", target_domain.TargetTypeWebhook, false)
 
 	tests := []struct {
 		name        string
@@ -175,7 +175,7 @@ func assertSetExecutionResponse(t *testing.T, creationDate, setDate time.Time, e
 func TestServer_SetExecution_Response(t *testing.T) {
 	instance := integration.NewInstance(CTX)
 	isolatedIAMOwnerCTX := instance.WithAuthorizationToken(CTX, integration.UserTypeIAMOwner)
-	targetResp := instance.CreateTargetWithoutPayloadType(isolatedIAMOwnerCTX, t, "", "https://notexisting", target_domain.TargetTypeWebhook, false)
+	targetResp := instance.CreateTargetWithoutPayloadType(isolatedIAMOwnerCTX, t, "", "https://example.com", target_domain.TargetTypeWebhook, false)
 
 	tests := []struct {
 		name        string
@@ -319,7 +319,7 @@ func TestServer_SetExecution_Response(t *testing.T) {
 func TestServer_SetExecution_Event(t *testing.T) {
 	instance := integration.NewInstance(CTX)
 	isolatedIAMOwnerCTX := instance.WithAuthorizationToken(CTX, integration.UserTypeIAMOwner)
-	targetResp := instance.CreateTargetWithoutPayloadType(isolatedIAMOwnerCTX, t, "", "https://notexisting", target_domain.TargetTypeWebhook, false)
+	targetResp := instance.CreateTargetWithoutPayloadType(isolatedIAMOwnerCTX, t, "", "https://example.com", target_domain.TargetTypeWebhook, false)
 
 	tests := []struct {
 		name        string
@@ -482,7 +482,7 @@ func TestServer_SetExecution_Event(t *testing.T) {
 func TestServer_SetExecution_Function(t *testing.T) {
 	instance := integration.NewInstance(CTX)
 	isolatedIAMOwnerCTX := instance.WithAuthorizationToken(CTX, integration.UserTypeIAMOwner)
-	targetResp := instance.CreateTargetWithoutPayloadType(isolatedIAMOwnerCTX, t, "", "https://notexisting", target_domain.TargetTypeWebhook, false)
+	targetResp := instance.CreateTargetWithoutPayloadType(isolatedIAMOwnerCTX, t, "", "https://example.com", target_domain.TargetTypeWebhook, false)
 
 	tests := []struct {
 		name        string

internal/api/grpc/server/connect_middleware/execution_interceptor.go

@@ -13,6 +13,7 @@ import (
 	"github.com/zitadel/zitadel/internal/api/authz"
 	http_utils "github.com/zitadel/zitadel/internal/api/http"
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/execution"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 	"github.com/zitadel/zitadel/internal/telemetry/tracing"
@@ -26,12 +27,12 @@ var headersToForward = map[string]bool{
 	strings.ToLower(http_utils.Origin):        true,
 }
 
-func ExecutionHandler(alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey) connect.UnaryInterceptorFunc {
+func ExecutionHandler(alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey, deniedIPList []denylist.AddressChecker) connect.UnaryInterceptorFunc {
 	return func(handler connect.UnaryFunc) connect.UnaryFunc {
 		return func(ctx context.Context, req connect.AnyRequest) (_ connect.AnyResponse, err error) {
 
 			requestTargets := execution.QueryExecutionTargetsForRequest(ctx, req.Spec().Procedure)
-			handledReq, err := executeTargetsForRequest(ctx, requestTargets, req.Spec().Procedure, req, alg, activeSigningKey)
+			handledReq, err := executeTargetsForRequest(ctx, requestTargets, req.Spec().Procedure, req, alg, activeSigningKey, deniedIPList)
 			if err != nil {
 				return nil, err
 			}
@@ -42,12 +43,12 @@ func ExecutionHandler(alg crypto.EncryptionAlgorithm, activeSigningKey execution
 			}
 
 			responseTargets := execution.QueryExecutionTargetsForResponse(ctx, req.Spec().Procedure)
-			return executeTargetsForResponse(ctx, responseTargets, req.Spec().Procedure, handledReq, response, alg, activeSigningKey)
+			return executeTargetsForResponse(ctx, responseTargets, req.Spec().Procedure, handledReq, response, alg, activeSigningKey, deniedIPList)
 		}
 	}
 }
 
-func executeTargetsForRequest(ctx context.Context, targets []target_domain.Target, fullMethod string, req connect.AnyRequest, alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey) (_ connect.AnyRequest, err error) {
+func executeTargetsForRequest(ctx context.Context, targets []target_domain.Target, fullMethod string, req connect.AnyRequest, alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey, deniedIPList []denylist.AddressChecker) (_ connect.AnyRequest, err error) {
 	ctx, span := tracing.NewSpan(ctx)
 	defer func() { span.EndWithError(err) }()
 
@@ -67,14 +68,14 @@ func executeTargetsForRequest(ctx context.Context, targets []target_domain.Targe
 		Headers:    SetRequestHeaders(req.Header()),
 	}
 
-	_, err = execution.CallTargets(ctx, targets, info, alg, activeSigningKey)
+	_, err = execution.CallTargets(ctx, targets, info, alg, activeSigningKey, deniedIPList)
 	if err != nil {
 		return nil, err
 	}
 	return req, nil
 }
 
-func executeTargetsForResponse(ctx context.Context, targets []target_domain.Target, fullMethod string, req connect.AnyRequest, resp connect.AnyResponse, alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey) (_ connect.AnyResponse, err error) {
+func executeTargetsForResponse(ctx context.Context, targets []target_domain.Target, fullMethod string, req connect.AnyRequest, resp connect.AnyResponse, alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey, deniedIPList []denylist.AddressChecker) (_ connect.AnyResponse, err error) {
 	ctx, span := tracing.NewSpan(ctx)
 	defer func() { span.EndWithError(err) }()
 
@@ -95,7 +96,7 @@ func executeTargetsForResponse(ctx context.Context, targets []target_domain.Targ
 		Headers:    SetRequestHeaders(req.Header()),
 	}
 
-	_, err = execution.CallTargets(ctx, targets, info, alg, activeSigningKey)
+	_, err = execution.CallTargets(ctx, targets, info, alg, activeSigningKey, deniedIPList)
 	if err != nil {
 		return nil, err
 	}

internal/api/grpc/server/connect_middleware/execution_interceptor_test.go

@@ -21,6 +21,7 @@ import (
 	"google.golang.org/protobuf/types/known/structpb"
 
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/execution"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 )
@@ -74,6 +75,10 @@ func newMockContextInfoResponse(fullMethod, request, response string) *ContextIn
 }
 
 func Test_executeTargetsForGRPCFullMethod_request(t *testing.T) {
+	deniedLocalhost, err := denylist.NewHostChecker("127.0.0.1")
+	require.NoError(t, err)
+	deniedIPs := []denylist.AddressChecker{deniedLocalhost}
+
 	type target struct {
 		reqBody             execution.ContextInfo
 		sleep               time.Duration
@@ -89,9 +94,10 @@ func Test_executeTargetsForGRPCFullMethod_request(t *testing.T) {
 		fullMethod             string
 		req                    connect.AnyRequest
 		getActiveSigningWebKey execution.GetActiveSigningWebKey
+		deniedIPs              []denylist.AddressChecker
 	}
 	type res struct {
-		want    interface{}
+		want    any
 		wantErr bool
 	}
 	tests := []struct {
@@ -286,6 +292,37 @@ func Test_executeTargetsForGRPCFullMethod_request(t *testing.T) {
 				want: newMockContentRequest("content1"),
 			},
 		},
+		{
+			"when target endpoint is in deny list should return error",
+			args{
+				ctx:        context.Background(),
+				fullMethod: "/service/method",
+				executionTargets: []target_domain.Target{
+					{
+						ExecutionID:      "request./zitadel.session.v2.SessionService/SetSession",
+						TargetID:         "target",
+						TargetType:       target_domain.TargetTypeCall,
+						Timeout:          time.Minute,
+						InterruptOnError: true,
+						Endpoint:         "127.0.0.1",
+					},
+				},
+				targets: []target{
+					{
+						reqBody:             newMockContextInfoRequest("/service/method", "content"),
+						respBody:            newMockContentResponse("content1"),
+						sleep:               0,
+						statusCode:          http.StatusOK,
+						requestVerification: validateJSONPayload,
+					},
+				},
+				req:       newMockContentRequest("content"),
+				deniedIPs: deniedIPs,
+			},
+			res{
+				wantErr: true,
+			},
+		},
 		{
 			"target async, timeout",
 			args{
@@ -631,6 +668,7 @@ func Test_executeTargetsForGRPCFullMethod_request(t *testing.T) {
 				tt.args.req,
 				nil,
 				tt.args.getActiveSigningWebKey,
+				tt.args.deniedIPs,
 			)
 
 			if tt.res.wantErr {
@@ -736,6 +774,9 @@ func validateJWEPayload(t *testing.T) func(expected, sent []byte) bool {
 }
 
 func Test_executeTargetsForGRPCFullMethod_response(t *testing.T) {
+	deniedLocalhost, err := denylist.NewHostChecker("127.0.0.1")
+	require.NoError(t, err)
+	deniedIPs := []denylist.AddressChecker{deniedLocalhost}
 	type target struct {
 		reqBody    execution.ContextInfo
 		sleep      time.Duration
@@ -750,6 +791,7 @@ func Test_executeTargetsForGRPCFullMethod_response(t *testing.T) {
 		fullMethod       string
 		req              connect.AnyRequest
 		resp             connect.AnyResponse
+		deniedIPs        []denylist.AddressChecker
 	}
 	type res struct {
 		want    interface{}
@@ -844,6 +886,37 @@ func Test_executeTargetsForGRPCFullMethod_response(t *testing.T) {
 				want: newMockContentResponse("response1"),
 			},
 		},
+		{
+			"when target endpoint is in deny list should return error",
+			args{
+				ctx:        context.Background(),
+				fullMethod: "/service/method",
+				executionTargets: []target_domain.Target{
+					{
+						ExecutionID:      "response./zitadel.session.v2.SessionService/SetSession",
+						TargetID:         "target",
+						TargetType:       target_domain.TargetTypeCall,
+						Timeout:          time.Minute,
+						InterruptOnError: true,
+						Endpoint:         "127.0.0.1",
+					},
+				},
+				targets: []target{
+					{
+						reqBody:    newMockContextInfoResponse("/service/method", "request", "response"),
+						respBody:   newMockContentResponse("response1"),
+						sleep:      0,
+						statusCode: http.StatusOK,
+					},
+				},
+				req:       newMockContentRequest("request"),
+				resp:      newMockContentResponse("response"),
+				deniedIPs: deniedIPs,
+			},
+			res{
+				wantErr: true,
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -869,6 +942,7 @@ func Test_executeTargetsForGRPCFullMethod_response(t *testing.T) {
 				tt.args.resp,
 				nil,
 				mockGetActiveSigningWebKey(),
+				tt.args.deniedIPs,
 			)
 
 			if tt.res.wantErr {

internal/api/grpc/server/middleware/execution_interceptor.go

@@ -13,16 +13,17 @@ import (
 	"github.com/zitadel/zitadel/internal/api/authz"
 	"github.com/zitadel/zitadel/internal/api/grpc/server/connect_middleware"
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/execution"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 	"github.com/zitadel/zitadel/internal/telemetry/tracing"
 )
 
-func ExecutionHandler(alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey) grpc.UnaryServerInterceptor {
+func ExecutionHandler(alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey, deniedIPList []denylist.AddressChecker) grpc.UnaryServerInterceptor {
 	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
 		requestTargets := execution.QueryExecutionTargetsForRequest(ctx, info.FullMethod)
 		// call targets otherwise return req
-		handledReq, err := executeTargetsForRequest(ctx, requestTargets, info.FullMethod, req, alg, activeSigningKey)
+		handledReq, err := executeTargetsForRequest(ctx, requestTargets, info.FullMethod, req, alg, activeSigningKey, deniedIPList)
 		if err != nil {
 			return nil, err
 		}
@@ -33,11 +34,11 @@ func ExecutionHandler(alg crypto.EncryptionAlgorithm, activeSigningKey execution
 		}
 
 		responseTargets := execution.QueryExecutionTargetsForResponse(ctx, info.FullMethod)
-		return executeTargetsForResponse(ctx, responseTargets, info.FullMethod, handledReq, response, alg, activeSigningKey)
+		return executeTargetsForResponse(ctx, responseTargets, info.FullMethod, handledReq, response, alg, activeSigningKey, deniedIPList)
 	}
 }
 
-func executeTargetsForRequest(ctx context.Context, targets []target_domain.Target, fullMethod string, req interface{}, alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey) (_ interface{}, err error) {
+func executeTargetsForRequest(ctx context.Context, targets []target_domain.Target, fullMethod string, req any, alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey, deniedIPList []denylist.AddressChecker) (_ interface{}, err error) {
 	ctx, span := tracing.NewSpan(ctx)
 	defer func() { span.EndWithError(err) }()
 
@@ -58,10 +59,10 @@ func executeTargetsForRequest(ctx context.Context, targets []target_domain.Targe
 		Headers:    connect_middleware.SetRequestHeaders(md),
 	}
 
-	return execution.CallTargets(ctx, targets, info, alg, activeSigningKey)
+	return execution.CallTargets(ctx, targets, info, alg, activeSigningKey, deniedIPList)
 }
 
-func executeTargetsForResponse(ctx context.Context, targets []target_domain.Target, fullMethod string, req, resp interface{}, alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey) (_ interface{}, err error) {
+func executeTargetsForResponse(ctx context.Context, targets []target_domain.Target, fullMethod string, req, resp interface{}, alg crypto.EncryptionAlgorithm, activeSigningKey execution.GetActiveSigningWebKey, deniedIPList []denylist.AddressChecker) (_ interface{}, err error) {
 	ctx, span := tracing.NewSpan(ctx)
 	defer func() { span.EndWithError(err) }()
 
@@ -83,7 +84,7 @@ func executeTargetsForResponse(ctx context.Context, targets []target_domain.Targ
 		Headers:    connect_middleware.SetRequestHeaders(md),
 	}
 
-	return execution.CallTargets(ctx, targets, info, alg, activeSigningKey)
+	return execution.CallTargets(ctx, targets, info, alg, activeSigningKey, deniedIPList)
 }
 
 var _ execution.ContextInfo = &ContextInfoRequest{}

internal/api/grpc/server/middleware/execution_interceptor_test.go

@@ -20,6 +20,7 @@ import (
 	"google.golang.org/protobuf/types/known/structpb"
 
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/execution"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 )
@@ -63,6 +64,10 @@ func newMockContextInfoResponse(fullMethod, request, response string) *ContextIn
 }
 
 func Test_executeTargetsForGRPCFullMethod_request(t *testing.T) {
+	deniedLocalhost, err := denylist.NewHostChecker("127.0.0.1")
+	require.NoError(t, err)
+	deniedIPs := []denylist.AddressChecker{deniedLocalhost}
+
 	type target struct {
 		reqBody             execution.ContextInfo
 		sleep               time.Duration
@@ -78,6 +83,7 @@ func Test_executeTargetsForGRPCFullMethod_request(t *testing.T) {
 		fullMethod             string
 		req                    interface{}
 		getActiveSigningWebKey execution.GetActiveSigningWebKey
+		deniedIPs              []denylist.AddressChecker
 	}
 	type res struct {
 		want    interface{}
@@ -275,6 +281,36 @@ func Test_executeTargetsForGRPCFullMethod_request(t *testing.T) {
 				want: newMockContentRequest("content1"),
 			},
 		},
+		{
+			"when target endpoint is in denylist should return error",
+			args{
+				ctx:        context.Background(),
+				fullMethod: "/service/method",
+				executionTargets: []target_domain.Target{
+					{
+						ExecutionID:      "request./zitadel.session.v2.SessionService/SetSession",
+						TargetID:         "target",
+						TargetType:       target_domain.TargetTypeCall,
+						Timeout:          time.Minute,
+						InterruptOnError: true,
+					},
+				},
+				targets: []target{
+					{
+						reqBody:             newMockContextInfoRequest("/service/method", "content"),
+						respBody:            newMockContentRequest("content1"),
+						sleep:               0,
+						statusCode:          http.StatusOK,
+						requestVerification: validateJSONPayload,
+					},
+				},
+				req:       newMockContentRequest("content"),
+				deniedIPs: deniedIPs,
+			},
+			res{
+				wantErr: true,
+			},
+		},
 		{
 			"target async, timeout",
 			args{
@@ -620,6 +656,7 @@ func Test_executeTargetsForGRPCFullMethod_request(t *testing.T) {
 				tt.args.req,
 				nil,
 				tt.args.getActiveSigningWebKey,
+				tt.args.deniedIPs,
 			)
 
 			if tt.res.wantErr {
@@ -725,6 +762,10 @@ func validateJWEPayload(t *testing.T) func(expected, sent []byte) bool {
 }
 
 func Test_executeTargetsForGRPCFullMethod_response(t *testing.T) {
+	deniedLocalhost, err := denylist.NewHostChecker("127.0.0.1")
+	require.NoError(t, err)
+	deniedIPs := []denylist.AddressChecker{deniedLocalhost}
+
 	type target struct {
 		reqBody    execution.ContextInfo
 		sleep      time.Duration
@@ -739,6 +780,7 @@ func Test_executeTargetsForGRPCFullMethod_response(t *testing.T) {
 		fullMethod       string
 		req              interface{}
 		resp             interface{}
+		deniedIPs        []denylist.AddressChecker
 	}
 	type res struct {
 		want    interface{}
@@ -833,6 +875,36 @@ func Test_executeTargetsForGRPCFullMethod_response(t *testing.T) {
 				want: newMockContentRequest("response1"),
 			},
 		},
+		{
+			"when target endpoint is in deny list should return error",
+			args{
+				ctx:        context.Background(),
+				fullMethod: "/service/method",
+				executionTargets: []target_domain.Target{
+					{
+						ExecutionID:      "response./zitadel.session.v2.SessionService/SetSession",
+						TargetID:         "target",
+						TargetType:       target_domain.TargetTypeCall,
+						Timeout:          time.Minute,
+						InterruptOnError: true,
+					},
+				},
+				targets: []target{
+					{
+						reqBody:    newMockContextInfoResponse("/service/method", "request", "response"),
+						respBody:   newMockContentRequest("response1"),
+						sleep:      0,
+						statusCode: http.StatusOK,
+					},
+				},
+				req:       newMockContentRequest("request"),
+				resp:      newMockContentRequest("response"),
+				deniedIPs: deniedIPs,
+			},
+			res{
+				wantErr: true,
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -858,6 +930,7 @@ func Test_executeTargetsForGRPCFullMethod_response(t *testing.T) {
 				tt.args.resp,
 				nil,
 				mockGetActiveSigningWebKey(),
+				tt.args.deniedIPs,
 			)
 
 			if tt.res.wantErr {

internal/api/grpc/server/server.go

@@ -16,6 +16,7 @@ import (
 	grpc_api "github.com/zitadel/zitadel/internal/api/grpc"
 	"github.com/zitadel/zitadel/internal/api/grpc/server/middleware"
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/i18n"
 	"github.com/zitadel/zitadel/internal/logstore"
 	"github.com/zitadel/zitadel/internal/logstore/record"
@@ -64,6 +65,7 @@ func CreateServer(
 	accessSvc *logstore.Service[*record.AccessLog],
 	targetEncAlg crypto.EncryptionAlgorithm,
 	translator *i18n.Translator,
+	deniedIPList []denylist.AddressChecker,
 ) *grpc.Server {
 	metricTypes := []metrics.MetricType{metrics.MetricTypeTotalCount, metrics.MetricTypeRequestCount, metrics.MetricTypeStatusCode}
 	serverOptions := []grpc.ServerOption{
@@ -80,7 +82,7 @@ func CreateServer(
 				middleware.AuthorizationInterceptor(verifier, systemAuthz, authConfig),
 				middleware.TranslationHandler(),
 				middleware.QuotaExhaustedInterceptor(accessSvc, system_pb.SystemService_ServiceDesc.ServiceName),
-				middleware.ExecutionHandler(targetEncAlg, queries.GetActiveSigningWebKey),
+				middleware.ExecutionHandler(targetEncAlg, queries.GetActiveSigningWebKey, deniedIPList),
 				middleware.ValidationHandler(),
 				middleware.ServiceHandler(),
 				middleware.ActivityInterceptor(),

internal/api/oidc/userinfo.go

@@ -461,7 +461,7 @@ func (s *Server) userinfoFlows(ctx context.Context, qu *query.OIDCUserInfo, user
 		UserGrants:   qu.UserGrants,
 	}
 
-	resp, err := execution.CallTargets(ctx, executionTargets, info, s.targetEncryptionAlgorithm, s.query.GetActiveSigningWebKey)
+	resp, err := execution.CallTargets(ctx, executionTargets, info, s.targetEncryptionAlgorithm, s.query.GetActiveSigningWebKey, s.command.ActionsV2DenyList)
 	if err != nil {
 		return err
 	}

internal/api/saml/storage.go

@@ -401,7 +401,7 @@ func (p *Storage) getCustomAttributes(ctx context.Context, user *query.User, use
 		UserGrants: userGrants.UserGrants,
 	}
 
-	resp, err := execution.CallTargets(ctx, executionTargets, info, p.targetEncAlg, p.query.GetActiveSigningWebKey)
+	resp, err := execution.CallTargets(ctx, executionTargets, info, p.targetEncAlg, p.query.GetActiveSigningWebKey, p.command.ActionsV2DenyList)
 	if err != nil {
 		return nil, err
 	}

internal/command/action_v2_target.go

@@ -7,9 +7,11 @@ import (
 
 	"github.com/zitadel/zitadel/internal/command/preparation"
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore/v1/models"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
+	internal_net "github.com/zitadel/zitadel/internal/net"
 	"github.com/zitadel/zitadel/internal/repository/target"
 	"github.com/zitadel/zitadel/internal/zerrors"
 )
@@ -27,18 +29,22 @@ type AddTarget struct {
 	SigningKey string
 }
 
-func (a *AddTarget) IsValid() error {
+func (a *AddTarget) isValid(inputDenyList []denylist.AddressChecker, lookupFunc internal_net.IPLookupFunc) error {
 	if a.Name == "" {
 		return zerrors.ThrowInvalidArgument(nil, "COMMAND-ddqbm9us5p", "Errors.Target.Invalid")
 	}
 	if a.Timeout == 0 {
 		return zerrors.ThrowInvalidArgument(nil, "COMMAND-39f35d8uri", "Errors.Target.NoTimeout")
 	}
-	_, err := url.Parse(a.Endpoint)
+	parsedURL, err := url.Parse(a.Endpoint)
 	if err != nil || a.Endpoint == "" {
 		return zerrors.ThrowInvalidArgument(err, "COMMAND-1r2k6qo6wg", "Errors.Target.InvalidURL")
 	}
 
+	if err := denylist.IsHostBlocked(inputDenyList, parsedURL, lookupFunc); err != nil {
+		return zerrors.ThrowInvalidArgument(err, "COMMAND-NcJUKo", "Errors.Target.DeniedURL")
+	}
+
 	return nil
 }
 
@@ -47,7 +53,7 @@ func (c *Commands) AddTarget(ctx context.Context, add *AddTarget, resourceOwner
 		return time.Time{}, zerrors.ThrowInvalidArgument(nil, "COMMAND-brml926e2d", "Errors.IDMissing")
 	}
 
-	if err := add.IsValid(); err != nil {
+	if err := add.isValid(c.ActionsV2DenyList, c.IPLookupFunction); err != nil {
 		return time.Time{}, err
 	}
 
@@ -103,7 +109,7 @@ type ChangeTarget struct {
 	SigningKey           *string
 }
 
-func (a *ChangeTarget) IsValid() error {
+func (a *ChangeTarget) isValid(inputDenyList []denylist.AddressChecker, lookupFunc internal_net.IPLookupFunc) error {
 	if a.AggregateID == "" {
 		return zerrors.ThrowInvalidArgument(nil, "COMMAND-1l6ympeagp", "Errors.IDMissing")
 	}
@@ -114,11 +120,15 @@ func (a *ChangeTarget) IsValid() error {
 		return zerrors.ThrowInvalidArgument(nil, "COMMAND-08b39vdi57", "Errors.Target.NoTimeout")
 	}
 	if a.Endpoint != nil {
-		_, err := url.Parse(*a.Endpoint)
+		parsedURL, err := url.Parse(*a.Endpoint)
 		if err != nil || *a.Endpoint == "" {
 			return zerrors.ThrowInvalidArgument(err, "COMMAND-jsbaera7b6", "Errors.Target.InvalidURL")
 		}
+		if err := denylist.IsHostBlocked(inputDenyList, parsedURL, lookupFunc); err != nil {
+			return zerrors.ThrowInvalidArgument(err, "COMMAND-jKbbu2", "Errors.Target.DeniedURL")
+		}
 	}
+
 	return nil
 }
 
@@ -126,7 +136,7 @@ func (c *Commands) ChangeTarget(ctx context.Context, change *ChangeTarget, resou
 	if resourceOwner == "" {
 		return time.Time{}, zerrors.ThrowInvalidArgument(nil, "COMMAND-zqibgg0wwh", "Errors.IDMissing")
 	}
-	if err := change.IsValid(); err != nil {
+	if err := change.isValid(c.ActionsV2DenyList, c.IPLookupFunction); err != nil {
 		return time.Time{}, err
 	}
 	existing, err := c.getTargetWriteModelByID(ctx, change.AggregateID, resourceOwner)

internal/command/action_v2_target_test.go

@@ -2,28 +2,37 @@ package command
 
 import (
 	"context"
+	"net"
 	"testing"
 	"time"
 
 	"github.com/muhlemmer/gu"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/eventstore"
 	"github.com/zitadel/zitadel/internal/eventstore/v1/models"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 	"github.com/zitadel/zitadel/internal/id"
 	"github.com/zitadel/zitadel/internal/id/mock"
+	internal_net "github.com/zitadel/zitadel/internal/net"
 	"github.com/zitadel/zitadel/internal/repository/target"
 	"github.com/zitadel/zitadel/internal/zerrors"
 )
 
 func TestCommands_AddTarget(t *testing.T) {
+	localhostAddrChecker, err := denylist.NewHostChecker("localhost")
+	require.NoError(t, err)
+
 	type fields struct {
 		eventstore                  func(t *testing.T) *eventstore.Eventstore
 		idGenerator                 id.Generator
 		newEncryptedCodeWithDefault encryptedCodeWithDefaultFunc
 		defaultSecretGenerators     *SecretGenerators
+		denyList                    []denylist.AddressChecker
+		lookupFunc                  internal_net.IPLookupFunc
 	}
 	type args struct {
 		ctx           context.Context
@@ -120,6 +129,28 @@ func TestCommands_AddTarget(t *testing.T) {
 				err: zerrors.IsErrorInvalidArgument,
 			},
 		},
+		{
+			"ip not allowed, error",
+			fields{
+				eventstore: expectEventstore(),
+				denyList:   []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("127.0.0.1")}, nil
+				},
+			},
+			args{
+				ctx: context.Background(),
+				add: &AddTarget{
+					Name:     "name",
+					Timeout:  time.Second,
+					Endpoint: "http://localhost",
+				},
+				resourceOwner: "instance",
+			},
+			res{
+				err: zerrors.IsErrorInvalidArgument,
+			},
+		},
 		{
 			"unique constraint failed, error",
 			fields{
@@ -147,6 +178,10 @@ func TestCommands_AddTarget(t *testing.T) {
 				idGenerator:                 mock.ExpectID(t, "id1"),
 				newEncryptedCodeWithDefault: mockEncryptedCodeWithDefault("12345678", time.Hour),
 				defaultSecretGenerators:     &SecretGenerators{},
+				denyList:                    []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -174,6 +209,10 @@ func TestCommands_AddTarget(t *testing.T) {
 					),
 				),
 				idGenerator: mock.ExpectID(t, "id1"),
+				denyList:    []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -201,6 +240,10 @@ func TestCommands_AddTarget(t *testing.T) {
 				idGenerator:                 mock.ExpectID(t, "id1"),
 				newEncryptedCodeWithDefault: mockEncryptedCodeWithDefault("12345678", time.Hour),
 				defaultSecretGenerators:     &SecretGenerators{},
+				denyList:                    []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -233,6 +276,10 @@ func TestCommands_AddTarget(t *testing.T) {
 				idGenerator:                 mock.ExpectID(t, "id1"),
 				newEncryptedCodeWithDefault: mockEncryptedCodeWithDefault("12345678", time.Hour),
 				defaultSecretGenerators:     &SecretGenerators{},
+				denyList:                    []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -258,6 +305,7 @@ func TestCommands_AddTarget(t *testing.T) {
 				idGenerator:                 tt.fields.idGenerator,
 				newEncryptedCodeWithDefault: tt.fields.newEncryptedCodeWithDefault,
 				defaultSecretGenerators:     tt.fields.defaultSecretGenerators,
+				ActionsV2DenyList:           tt.fields.denyList,
 			}
 			_, err := c.AddTarget(tt.args.ctx, tt.args.add, tt.args.resourceOwner)
 			if tt.res.err == nil {
@@ -274,10 +322,15 @@ func TestCommands_AddTarget(t *testing.T) {
 }
 
 func TestCommands_ChangeTarget(t *testing.T) {
+	localhostAddrChecker, err := denylist.NewHostChecker("localhost")
+	require.NoError(t, err)
+
 	type fields struct {
 		eventstore                  func(t *testing.T) *eventstore.Eventstore
 		newEncryptedCodeWithDefault encryptedCodeWithDefaultFunc
 		defaultSecretGenerators     *SecretGenerators
+		denyList                    []denylist.AddressChecker
+		lookupFunc                  internal_net.IPLookupFunc
 	}
 	type args struct {
 		ctx           context.Context
@@ -385,12 +438,39 @@ func TestCommands_ChangeTarget(t *testing.T) {
 				err: zerrors.IsErrorInvalidArgument,
 			},
 		},
+		{
+			"ip not allowed, error",
+			fields{
+				eventstore: expectEventstore(),
+				denyList:   []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("127.0.0.1")}, nil
+				},
+			},
+			args{
+				ctx: context.Background(),
+				change: &ChangeTarget{
+					ObjectRoot: models.ObjectRoot{
+						AggregateID: "id1",
+					},
+					Endpoint: gu.Ptr("http://localhost"),
+				},
+				resourceOwner: "instance",
+			},
+			res{
+				err: zerrors.IsErrorInvalidArgument,
+			},
+		},
 		{
 			"not found, error",
 			fields{
 				eventstore: expectEventstore(
 					expectFilter(),
 				),
+				denyList: []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -416,6 +496,10 @@ func TestCommands_ChangeTarget(t *testing.T) {
 						),
 					),
 				),
+				denyList: []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -448,6 +532,10 @@ func TestCommands_ChangeTarget(t *testing.T) {
 						),
 					),
 				),
+				denyList: []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -481,6 +569,10 @@ func TestCommands_ChangeTarget(t *testing.T) {
 						),
 					),
 				),
+				denyList: []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -525,6 +617,10 @@ func TestCommands_ChangeTarget(t *testing.T) {
 				),
 				newEncryptedCodeWithDefault: mockEncryptedCodeWithDefault("12345678", time.Hour),
 				defaultSecretGenerators:     &SecretGenerators{},
+				denyList:                    []denylist.AddressChecker{localhostAddrChecker},
+				lookupFunc: func(_ string) ([]net.IP, error) {
+					return []net.IP{[]byte("192.168.1.1")}, nil
+				},
 			},
 			args{
 				ctx: context.Background(),
@@ -551,6 +647,8 @@ func TestCommands_ChangeTarget(t *testing.T) {
 				eventstore:                  tt.fields.eventstore(t),
 				newEncryptedCodeWithDefault: tt.fields.newEncryptedCodeWithDefault,
 				defaultSecretGenerators:     tt.fields.defaultSecretGenerators,
+				ActionsV2DenyList:           tt.fields.denyList,
+				IPLookupFunction:            tt.fields.lookupFunc,
 			}
 			_, err := c.ChangeTarget(tt.args.ctx, tt.args.change, tt.args.resourceOwner)
 			if tt.res.err == nil {

internal/command/command.go

@@ -8,6 +8,7 @@ import (
 	"encoding/pem"
 	"fmt"
 	"math/big"
+	"net"
 	"net/http"
 	"slices"
 	"strconv"
@@ -24,9 +25,11 @@ import (
 	"github.com/zitadel/zitadel/internal/command/preparation"
 	sd "github.com/zitadel/zitadel/internal/config/systemdefaults"
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	"github.com/zitadel/zitadel/internal/eventstore"
 	"github.com/zitadel/zitadel/internal/id"
+	internal_net "github.com/zitadel/zitadel/internal/net"
 	"github.com/zitadel/zitadel/internal/notification/senders"
 	"github.com/zitadel/zitadel/internal/static"
 	"github.com/zitadel/zitadel/internal/telemetry/tracing"
@@ -101,7 +104,9 @@ type Commands struct {
 	// so the query and cache overhead can be completely eliminated.
 	milestonesCompleted sync.Map
 
-	loginPaths LoginPaths
+	loginPaths        LoginPaths
+	ActionsV2DenyList []denylist.AddressChecker
+	IPLookupFunction  internal_net.IPLookupFunc
 }
 
 //go:generate mockgen -package command -destination ./mock_login_paths.go . LoginPaths
@@ -130,6 +135,7 @@ func StartCommands(
 	defaultAccessTokenLifetime, defaultRefreshTokenLifetime, defaultRefreshTokenIdleLifetime time.Duration,
 	defaultSecretGenerators *SecretGenerators,
 	loginPaths LoginPaths,
+	actionsDeniedHostList []denylist.AddressChecker,
 ) (repo *Commands, err error) {
 	if externalDomain == "" {
 		return nil, zerrors.ThrowInvalidArgument(nil, "COMMAND-Df21s", "no external domain specified")
@@ -215,9 +221,11 @@ func StartCommands(
 				WithHyphen: defaults.Multifactors.RecoveryCodes.WithHyphen,
 			},
 		},
-		GenerateDomain: domain.NewGeneratedInstanceDomain,
-		caches:         caches,
-		loginPaths:     loginPaths,
+		GenerateDomain:    domain.NewGeneratedInstanceDomain,
+		caches:            caches,
+		loginPaths:        loginPaths,
+		ActionsV2DenyList: actionsDeniedHostList,
+		IPLookupFunction:  net.LookupIP,
 	}
 
 	if defaultSecretGenerators != nil && defaultSecretGenerators.ClientSecret != nil {

internal/denylist/denylist.go

@@ -0,0 +1,47 @@
+package denylist
+
+import (
+	"net"
+	"reflect"
+
+	"github.com/mitchellh/mapstructure"
+)
+
+type AddressChecker interface {
+	IsDenied([]net.IP, string) error
+}
+
+func ParseDenyList(inputList []string) ([]AddressChecker, error) {
+	var toReturn []AddressChecker
+	for _, input := range inputList {
+		parsed, parseErr := NewHostChecker(input)
+		if parseErr != nil {
+			return nil, parseErr
+		}
+		if parsed != nil {
+			toReturn = append(toReturn, parsed)
+		}
+	}
+	return toReturn, nil
+}
+
+func DenyListDecodeHook(from, to reflect.Value) (interface{}, error) {
+	if to.Type() != reflect.TypeFor[[]AddressChecker]() {
+		return from.Interface(), nil
+	}
+	var inputDenyList []string
+	decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
+		DecodeHook: mapstructure.ComposeDecodeHookFunc(
+			mapstructure.StringToSliceHookFunc(","),
+		),
+		WeaklyTypedInput: true,
+		Result:           &inputDenyList,
+	})
+	if err != nil {
+		return nil, err
+	}
+	if err = decoder.Decode(from.Interface()); err != nil {
+		return nil, err
+	}
+	return ParseDenyList(inputDenyList)
+}

internal/denylist/error.go

@@ -0,0 +1,26 @@
+package denylist
+
+import (
+	"errors"
+	"fmt"
+)
+
+type AddressDeniedError struct {
+	deniedBy string
+}
+
+func NewAddressDeniedError(deniedBy string) *AddressDeniedError {
+	return &AddressDeniedError{deniedBy: deniedBy}
+}
+
+func (e *AddressDeniedError) Error() string {
+	return fmt.Sprintf("address is denied by '%s'", e.deniedBy)
+}
+
+func (e *AddressDeniedError) Is(target error) bool {
+	var addressDeniedErr *AddressDeniedError
+	if !errors.As(target, &addressDeniedErr) {
+		return false
+	}
+	return e.deniedBy == addressDeniedErr.deniedBy
+}

internal/denylist/host_checker.go

@@ -0,0 +1,69 @@
+package denylist
+
+import (
+	"net"
+	"net/url"
+
+	internal_net "github.com/zitadel/zitadel/internal/net"
+)
+
+var _ AddressChecker = (*HostChecker)(nil)
+
+type HostChecker struct {
+	Net    *net.IPNet
+	IP     net.IP
+	Domain string
+}
+
+func NewHostChecker(entry string) (AddressChecker, error) {
+	if entry == "" {
+		return nil, nil
+	}
+	_, network, err := net.ParseCIDR(entry)
+	if err == nil {
+		return &HostChecker{Net: network}, nil
+	}
+	if ip := net.ParseIP(entry); ip != nil {
+		return &HostChecker{IP: ip}, nil
+	}
+	return &HostChecker{Domain: entry}, nil
+}
+
+func (c *HostChecker) IsDenied(ips []net.IP, address string) error {
+	// if the address matches the domain, no additional checks as needed
+	if c.Domain == address {
+		return NewAddressDeniedError(c.Domain)
+	}
+	// otherwise we need to check on ips (incl. the resolved ips of the host)
+	for _, ip := range ips {
+		if c.Net != nil && c.Net.Contains(ip) {
+			return NewAddressDeniedError(c.Net.String())
+		}
+		if c.IP != nil && c.IP.Equal(ip) {
+			return NewAddressDeniedError(c.IP.String())
+		}
+	}
+	return nil
+}
+
+// IsHostBlocked checks address against denyList. If a match is found, an [AddressDeniedError] will be returned
+// Takes an input lookupFunc to convert address to a list of IP addresses.
+// If lookupFunc is nil, it defaults to [net.LookupIP]
+func IsHostBlocked(denyList []AddressChecker, address *url.URL, lookupFunc internal_net.IPLookupFunc) error {
+	if lookupFunc == nil {
+		lookupFunc = net.LookupIP
+	}
+
+	host := address.Hostname()
+	ips, err := internal_net.HostnameToIPList(host, lookupFunc)
+	if err != nil {
+		return err
+	}
+
+	for _, denied := range denyList {
+		if err := denied.IsDenied(ips, host); err != nil {
+			return err
+		}
+	}
+	return nil
+}

internal/denylist/host_checker_test.go

@@ -0,0 +1,122 @@
+package denylist
+
+import (
+	"io"
+	"net"
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/zitadel/zitadel/internal/zerrors"
+)
+
+func TestIsHostBlocked(t *testing.T) {
+	t.Parallel()
+	var denyList = []AddressChecker{
+		mustNewHostChecker(t, "192.168.5.0/24"),
+		mustNewHostChecker(t, "127.0.0.1"),
+		mustNewHostChecker(t, "test.com"),
+	}
+	type fields struct {
+		lookup func(host string) ([]net.IP, error)
+	}
+	type args struct {
+		address *url.URL
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   error
+	}{
+		{
+			name: "in range",
+			args: args{
+				address: mustNewURL(t, "https://192.168.5.4/hodor"),
+			},
+			want: NewAddressDeniedError("192.168.5.0/24"),
+		},
+		{
+			name: "exact ip",
+			args: args{
+				address: mustNewURL(t, "http://127.0.0.1:8080/hodor"),
+			},
+			want: NewAddressDeniedError("127.0.0.1"),
+		},
+		{
+			name: "address match",
+			fields: fields{
+				lookup: func(host string) ([]net.IP, error) {
+					return []net.IP{net.ParseIP("194.264.52.4")}, nil
+				},
+			},
+			args: args{
+				address: mustNewURL(t, "https://test.com:42/hodor"),
+			},
+			want: NewAddressDeniedError("test.com"),
+		},
+		{
+			name: "address not match",
+			fields: fields{
+				lookup: func(host string) ([]net.IP, error) {
+					return []net.IP{net.ParseIP("194.264.52.4")}, nil
+				},
+			},
+			args: args{
+				address: mustNewURL(t, "https://test2.com/hodor"),
+			},
+			want: nil,
+		},
+		{
+			name: "looked up ip matches",
+			fields: fields{
+				lookup: func(host string) ([]net.IP, error) {
+					return []net.IP{net.ParseIP("127.0.0.1")}, nil
+				},
+			},
+			args: args{
+				address: mustNewURL(t, "https://test2.com/hodor"),
+			},
+			want: NewAddressDeniedError("127.0.0.1"),
+		},
+		{
+			name: "lookup failure",
+			fields: fields{
+				lookup: func(host string) ([]net.IP, error) {
+					return nil, io.EOF
+				},
+			},
+			args: args{
+				address: mustNewURL(t, "https://test2.com/hodor"),
+			},
+			want: zerrors.ThrowInternal(io.EOF, "NET-4m9s2", "lookup failed"),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			got := IsHostBlocked(denyList, tt.args.address, tt.fields.lookup)
+			assert.ErrorIs(t, got, tt.want)
+		})
+	}
+}
+
+func mustNewHostChecker(t *testing.T, ip string) AddressChecker {
+	t.Helper()
+	checker, err := NewHostChecker(ip)
+	if err != nil {
+		t.Errorf("unable to parse cidr of %q because: %v", ip, err)
+		t.FailNow()
+	}
+	return checker
+}
+
+func mustNewURL(t *testing.T, raw string) *url.URL {
+	u, err := url.Parse(raw)
+	if err != nil {
+		t.Errorf("unable to parse address of %q because: %v", raw, err)
+		t.FailNow()
+	}
+	return u
+}

internal/execution/execution.go

@@ -9,7 +9,9 @@ import (
 	"encoding/json"
 	"encoding/pem"
 	"io"
+	"net"
 	"net/http"
+	"net/url"
 	"sync"
 	"time"
 
@@ -20,6 +22,7 @@ import (
 	zhttp "github.com/zitadel/zitadel/internal/api/http"
 	"github.com/zitadel/zitadel/internal/api/oidc/sign"
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/domain"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 	"github.com/zitadel/zitadel/internal/repository/execution"
@@ -43,7 +46,8 @@ func CallTargets(
 	info ContextInfo,
 	alg crypto.EncryptionAlgorithm,
 	activeSigningKey GetActiveSigningWebKey,
-) (_ interface{}, err error) {
+	deniedIPList []denylist.AddressChecker,
+) (_ any, err error) {
 	ctx, span := tracing.NewSpan(ctx)
 	defer func() { span.EndWithError(err) }()
 
@@ -54,7 +58,7 @@ func CallTargets(
 
 	for _, target := range targets {
 		// call the type of target
-		resp, err := CallTarget(ctx, target, info, alg, signerOnce, encrypters)
+		resp, err := CallTarget(ctx, target, info, alg, signerOnce, encrypters, deniedIPList)
 		// handle error if interrupt is set
 		logging.WithFields("instanceID", authz.GetInstance(ctx).InstanceID(), "target", target.GetTargetID()).OnError(err).Error("error calling target")
 		if err != nil && target.IsInterruptOnError() {
@@ -82,6 +86,7 @@ func CallTarget(
 	alg crypto.EncryptionAlgorithm,
 	signerOnce sign.SignerFunc,
 	encrypters *sync.Map,
+	deniedIPList []denylist.AddressChecker,
 ) (res []byte, err error) {
 	ctx, span := tracing.NewSpan(ctx)
 	defer func() { span.EndWithError(err) }()
@@ -90,6 +95,17 @@ func CallTarget(
 	if err != nil {
 		return nil, zerrors.ThrowInternal(err, "EXEC-thiiCh5b", "Errors.Internal")
 	}
+
+	if target.GetEndpoint() != "" {
+		endpointURL, err := url.Parse(target.GetEndpoint())
+		if err != nil {
+			return nil, zerrors.ThrowInvalidArgument(err, "EXEC-N5lu09", "Errors.Endpoint.Invalid")
+		}
+		if err := denylist.IsHostBlocked(deniedIPList, endpointURL, net.LookupIP); err != nil {
+			return nil, zerrors.ThrowInvalidArgument(err, "EXEC-N5lu09", "Errors.Endpoint.Denied")
+		}
+	}
+
 	body, err := payload(ctx, info.GetHTTPRequestBody(), target, signerOnce, encrypters)
 	if err != nil {
 		return nil, err

internal/execution/execution_test.go

@@ -24,6 +24,7 @@ import (
 	"github.com/zitadel/zitadel/internal/api/grpc/server/middleware"
 	"github.com/zitadel/zitadel/internal/api/oidc/sign"
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	"github.com/zitadel/zitadel/internal/execution"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 	"github.com/zitadel/zitadel/internal/zerrors"
@@ -405,7 +406,11 @@ func Test_CallTarget(t *testing.T) {
 			respBody, err := testServer(
 				t,
 				tt.args.server,
-				testCallTarget(tt.args.ctx, tt.args.info, tt.args.target, crypto.CreateMockEncryptionAlg(gomock.NewController(t)), tt.args.signer, &sync.Map{}),
+				testCallTarget(
+					tt.args.ctx, tt.args.info, tt.args.target,
+					crypto.CreateMockEncryptionAlg(gomock.NewController(t)), tt.args.signer, &sync.Map{},
+					[]denylist.AddressChecker{},
+				),
 			)
 			if tt.res.wantErr {
 				assert.Error(t, err)
@@ -418,6 +423,9 @@ func Test_CallTarget(t *testing.T) {
 }
 
 func Test_CallTargets(t *testing.T) {
+	deniedLocalhost, err := denylist.NewHostChecker("127.0.0.1")
+	require.NoError(t, err)
+	deniedIPs := []denylist.AddressChecker{deniedLocalhost}
 	type args struct {
 		ctx                    context.Context
 		info                   *middleware.ContextInfoRequest
@@ -426,17 +434,18 @@ func Test_CallTargets(t *testing.T) {
 		getActiveSigningWebKey func(*int32) execution.GetActiveSigningWebKey
 	}
 	type res struct {
-		ret     interface{}
+		ret     any
 		wantErr bool
 	}
 	tests := []struct {
-		name string
-		args args
-		res  res
+		name     string
+		denyList []denylist.AddressChecker
+		args     args
+		res      res
 	}{
 		{
-			"interrupt on status",
-			args{
+			name: "interrupt on status",
+			args: args{
 				ctx:  context.Background(),
 				info: requestContextInfo1,
 				servers: []*callTestServer{{
@@ -457,13 +466,13 @@ func Test_CallTargets(t *testing.T) {
 					{InterruptOnError: true},
 				},
 			},
-			res{
+			res: res{
 				wantErr: true,
 			},
 		},
 		{
-			"continue on status",
-			args{
+			name: "continue on status",
+			args: args{
 				ctx:  context.Background(),
 				info: requestContextInfo1,
 				servers: []*callTestServer{{
@@ -484,13 +493,13 @@ func Test_CallTargets(t *testing.T) {
 					{InterruptOnError: false},
 				},
 			},
-			res{
+			res: res{
 				ret: requestContextInfo1.GetContent(),
 			},
 		},
 		{
-			"interrupt on json error",
-			args{
+			name: "interrupt on json error",
+			args: args{
 				ctx:  context.Background(),
 				info: requestContextInfo1,
 				servers: []*callTestServer{{
@@ -511,13 +520,13 @@ func Test_CallTargets(t *testing.T) {
 					{InterruptOnError: true},
 				},
 			},
-			res{
+			res: res{
 				wantErr: true,
 			},
 		},
 		{
-			"continue on json error",
-			args{
+			name: "continue on json error",
+			args: args{
 				ctx:  context.Background(),
 				info: requestContextInfo1,
 				servers: []*callTestServer{{
@@ -537,13 +546,13 @@ func Test_CallTargets(t *testing.T) {
 					{InterruptOnError: false},
 					{InterruptOnError: false},
 				}},
-			res{
+			res: res{
 				ret: requestContextInfo1.GetContent(),
 			},
 		},
 		{
-			"multiple JWT/JWE targets, ok",
-			args{
+			name: "multiple JWT/JWE targets, ok",
+			args: args{
 				ctx:  context.Background(),
 				info: requestContextInfo1,
 				servers: []*callTestServer{{
@@ -573,10 +582,38 @@ func Test_CallTargets(t *testing.T) {
 				},
 				getActiveSigningWebKey: testActiveSingingWebKey,
 			},
-			res{
+			res: res{
 				ret: requestContextInfo1.GetContent(),
 			},
 		},
+		{
+			name:     "block request when target in denylist",
+			denyList: deniedIPs,
+			args: args{
+				ctx:  context.Background(),
+				info: requestContextInfo1,
+				servers: []*callTestServer{{
+					timeout:     time.Second,
+					method:      http.MethodPost,
+					expectBody:  validateJSONPayload(requestContextInfoBody1),
+					respondBody: requestContextInfoBody2,
+					statusCode:  http.StatusOK,
+				}, {
+					timeout:     time.Second,
+					method:      http.MethodPost,
+					expectBody:  validateJSONPayload(requestContextInfoBody1),
+					respondBody: []byte("just a string, not json"),
+					statusCode:  http.StatusOK,
+				}},
+				targets: []target_domain.Target{
+					{InterruptOnError: false},
+					{InterruptOnError: true},
+				},
+			},
+			res: res{
+				wantErr: true,
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -587,7 +624,9 @@ func Test_CallTargets(t *testing.T) {
 			}
 			respBody, err := testServers(t,
 				tt.args.servers,
-				testCallTargets(tt.args.ctx, tt.args.info, tt.args.targets, crypto.CreateMockEncryptionAlg(gomock.NewController(t)), getActiveSigningWebKey),
+				testCallTargets(
+					tt.args.ctx, tt.args.info, tt.args.targets,
+					crypto.CreateMockEncryptionAlg(gomock.NewController(t)), getActiveSigningWebKey, tt.denyList),
 			)
 			if tt.res.wantErr {
 				assert.Error(t, err)
@@ -691,10 +730,11 @@ func testCallTarget(ctx context.Context,
 	alg crypto.EncryptionAlgorithm,
 	signerOnce sign.SignerFunc,
 	encrypters *sync.Map,
+	actionsDenyList []denylist.AddressChecker,
 ) func(string) ([]byte, error) {
 	return func(url string) (r []byte, err error) {
 		target.Endpoint = url
-		return execution.CallTarget(ctx, target, info, alg, signerOnce, encrypters)
+		return execution.CallTarget(ctx, target, info, alg, signerOnce, encrypters, actionsDenyList)
 	}
 }
 
@@ -703,14 +743,15 @@ func testCallTargets(ctx context.Context,
 	target []target_domain.Target,
 	alg crypto.EncryptionAlgorithm,
 	activeSigningKey execution.GetActiveSigningWebKey,
-) func([]string) (interface{}, error) {
-	return func(urls []string) (interface{}, error) {
+	actionsDenyList []denylist.AddressChecker,
+) func([]string) (any, error) {
+	return func(urls []string) (any, error) {
 		targets := make([]target_domain.Target, len(target))
 		for i, t := range target {
 			t.Endpoint = urls[i]
 			targets[i] = t
 		}
-		return execution.CallTargets(ctx, targets, info, alg, activeSigningKey)
+		return execution.CallTargets(ctx, targets, info, alg, activeSigningKey, actionsDenyList)
 	}
 }
 
@@ -723,10 +764,6 @@ var requestContextInfo1 = &middleware.ContextInfoRequest{
 var requestContextInfoBody1 = []byte("{\"request\":{\"content\":\"request1\"}}")
 var requestContextInfoBody2 = []byte("{\"request\":{\"content\":\"request2\"}}")
 
-type request struct {
-	Request string `json:"request"`
-}
-
 func testErrorBody(code int, message string) []byte {
 	body := &execution.ErrorBody{ForwardedStatusCode: code, ForwardedErrorMessage: message}
 	data, _ := json.Marshal(body)

internal/execution/worker.go

@@ -10,6 +10,7 @@ import (
 	"github.com/riverqueue/river"
 
 	"github.com/zitadel/zitadel/internal/crypto"
+	"github.com/zitadel/zitadel/internal/denylist"
 	target_domain "github.com/zitadel/zitadel/internal/execution/target"
 	exec_repo "github.com/zitadel/zitadel/internal/repository/execution"
 )
@@ -46,7 +47,7 @@ func (w *Worker) Work(ctx context.Context, job *river.Job[*exec_repo.Request]) e
 		return river.JobCancel(fmt.Errorf("unable to unmarshal targets because %w", err))
 	}
 
-	_, err = CallTargets(ctx, targets, exec_repo.ContextInfoFromRequest(job.Args), w.targetEncAlg, w.activeSigningKey)
+	_, err = CallTargets(ctx, targets, exec_repo.ContextInfoFromRequest(job.Args), w.targetEncAlg, w.activeSigningKey, w.config.DenyList)
 	if err != nil {
 		// If there is an error returned from the targets, it means that the execution was interrupted
 		return river.JobCancel(fmt.Errorf("interruption during call of targets because %w", err))
@@ -61,6 +62,7 @@ type WorkerConfig struct {
 	Workers             uint8
 	TransactionDuration time.Duration
 	MaxTtl              time.Duration
+	DenyList            []denylist.AddressChecker
 }
 
 func NewWorker(

internal/net/net.go

@@ -0,0 +1,30 @@
+package net
+
+import (
+	builtin_net "net"
+
+	"github.com/zitadel/zitadel/internal/zerrors"
+)
+
+type IPLookupFunc func(string) ([]builtin_net.IP, error)
+
+// HostnameToIPList converts the input URL to a list [net.IP].
+//
+// Returns an internal error if the lookup fails.
+// Returns an invalid argument if the lookup function is nil
+func HostnameToIPList(hostname string, lookupFunc IPLookupFunc) ([]builtin_net.IP, error) {
+	ip := builtin_net.ParseIP(hostname)
+	ips := []builtin_net.IP{ip}
+	if ip != nil {
+		return ips, nil
+	}
+	// if the hostname is a domain, we need to check resolve the ip(s), since it might be denied
+	if lookupFunc == nil {
+		return nil, zerrors.ThrowInvalidArgument(nil, "NET-naSn77", "lookup function must not be nil")
+	}
+	ips, err := lookupFunc(hostname)
+	if err != nil {
+		return nil, zerrors.ThrowInternal(err, "NET-4m9s2", "lookup failed")
+	}
+	return ips, nil
+}

internal/net/net_test.go

@@ -0,0 +1,78 @@
+package net
+
+import (
+	builtin_net "net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/zitadel/zitadel/internal/zerrors"
+)
+
+func TestHostnameToIPList(t *testing.T) {
+	t.Parallel()
+	addrErr := &builtin_net.AddrError{Addr: "invalid.local", Err: "Invalid address"}
+	tests := []struct {
+		name        string
+		hostname    string
+		lookupFunc  IPLookupFunc
+		want        []builtin_net.IP
+		expectedErr error
+	}{
+		{
+			name:       "valid IP address",
+			hostname:   "192.168.1.1",
+			lookupFunc: nil,
+			want:       []builtin_net.IP{builtin_net.ParseIP("192.168.1.1")},
+		},
+		{
+			name:     "domain with lookup function",
+			hostname: "example.com",
+			lookupFunc: func(s string) ([]builtin_net.IP, error) {
+				return []builtin_net.IP{builtin_net.ParseIP("127.0.0.1")}, nil
+			},
+			want: []builtin_net.IP{builtin_net.ParseIP("127.0.0.1")},
+		},
+		{
+			name:        "domain without lookup function",
+			hostname:    "example.com",
+			lookupFunc:  nil,
+			want:        nil,
+			expectedErr: zerrors.ThrowInvalidArgument(nil, "NET-naSn77", "lookup function must not be nil"),
+		},
+		{
+			name:     "domain with lookup error",
+			hostname: "invalid.local",
+			lookupFunc: func(s string) ([]builtin_net.IP, error) {
+				return nil, addrErr
+			},
+			want:        nil,
+			expectedErr: zerrors.ThrowInternal(addrErr, "NET-4m9s2", "lookup failed"),
+		},
+		{
+			name:     "domain with multiple IPs",
+			hostname: "multi.example.com",
+			lookupFunc: func(s string) ([]builtin_net.IP, error) {
+				return []builtin_net.IP{
+					builtin_net.ParseIP("127.0.0.1"),
+					builtin_net.ParseIP("127.0.0.2"),
+				}, nil
+			},
+			want: []builtin_net.IP{
+				builtin_net.ParseIP("127.0.0.1"),
+				builtin_net.ParseIP("127.0.0.2"),
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			got, err := HostnameToIPList(tt.hostname, tt.lookupFunc)
+
+			require.ErrorIs(t, err, tt.expectedErr)
+			assert.ElementsMatch(t, got, tt.want)
+		})
+	}
+}