a17af0fe93
* fix(login): prevent external-IDP account pre-hijack in Login V1 (GHSA-738m-7888-jfv8) The Login V1 endpoint POST /ui/login/externaluser/option (handleExternalNotFoundOptionCheck) built the new external user's identity and "verified" flags directly from raw POST fields, without checking the server-side authReq.LinkingUsers state that a genuine, protocol-verified IDP callback populates. An unauthenticated attacker could forge that POST to create a real account bound to an arbitrary (IDPConfigID, ExternalUserID) - enabling account pre-hijack of a third party whose public external identifier (e.g. a GitHub numeric user id) was used, so the victim's own future "Sign in with X" logs into the attacker's pre-created account. Primary fix: - Reject the request when authReq.LinkingUsers is empty, mirroring the guarded sibling autoCreateExternalUser. - Source IDPConfigID/ExternalUserID and the email/phone "verified" flags from the trusted linkingUser (the real callback data) instead of the form; the verified flag only survives when the editable value still matches the IDP's. Profile fields (name, nickname, language, edited email/phone) still come from the form, which is the page's legitimate purpose. Secondary hardening: - Treat the OAuth error/error_description callback params as untrusted so a forged GET .../externalidp/callback?error=... can no longer trigger the local-auth fallback (RequestLocalAuth) and undermine the IDP-first login priority. Genuine code-exchange failures keep their existing handling. Tests: - Unit test for mapExternalNotFoundOptionFormDataToLoginUser proving forged identity/verified fields are ignored in favor of the trusted callback data. - A //go:build integration end-to-end reproduction driving the forged registration over raw HTTP and asserting the account is not created. Co-Authored-By: Claude Opus 4.8 <[email protected]> * fix(login): handle IDP error callback for logging, keep local-auth fallback Addresses review feedback (livio-a) on GHSA-738m-7888-jfv8: the OAuth error callback is not a security boundary. Blocking only the error= path added no protection (a garbage code triggers the same fallback), the downgrade only affects the attacker's own auth request, and a genuine IDP error on the callback should still fall back to local auth. - handleExternalLoginCallback: on an IDP error response, log it with context and route through externalAuthCallbackFailed so local-auth fallback still happens when the login policy allows it (previous behavior), instead of rendering a plain login error. The displayed message reuses the existing Errors.User.ExternalIDP.LoginFailedSwitchLocal via WrapIdPError. - Drop the now-unused Errors.ExternalIDP.AuthenticationFailed translation (would otherwise need all-language entries) and regenerate the login statik blob. - Reword the externalIDPCallbackData Error/ErrorDescription comment: logging-only, not a security decision. Co-Authored-By: Claude Opus 4.8 <[email protected]> --------- Co-authored-by: Claude Opus 4.8 <[email protected]> Co-authored-by: Livio Spring <[email protected]>
The Identity Infrastructure for Developers
ZITADEL is an open-source identity and access management platform built for teams that need more than basic auth. Whether you're securing a SaaS product, building a B2B platform, or self-hosting a production IAM stack — ZITADEL gives you everything out of the box: SSO, MFA, Passkeys, OIDC, SAML, SCIM, and a battle-tested multi-tenancy model.
No vendor lock-in. No compromise on control. Just a robust, API-first identity platform you can own.
🏡 Website | 💬 Chat | 📋 Docs | 🧑💻 Blog | 📞 Contact
Why ZITADEL
We built ZITADEL to handle the hardest IAM challenges at scale — starting with multi-tenancy.
| ZITADEL | FusionAuth | Keycloak | Auth0/Okta | |
|---|---|---|---|---|
| Open-source | ✅ | ❌ | ✅ | ❌ |
| Self-hostable | ✅ | ✅ | ✅ | ❌ |
| Infrastructure-level tenants | ✅ Instances (High scale) | ✅ Tenants | 🟡 Realms (Scaling limits) | ❌ (Multi-tenant = multi-account) |
| B2B Organizations | ✅ Native & Unlimited | 🟡 via Entity Management | ✅ (Recent addition) | 🟡 (Plan/Account dependent) |
| Full audit trail | ✅ Comprehensive Event Stream* | 🟡 Audit logs | 🟡 Audit logs | 🟡 Audit logs |
| Passkeys (FIDO2) | ✅ | ✅ | ✅ | ✅ |
| Actions / webhooks | ✅ | ✅ | 🟡 via SPI | ✅ |
| API-first (gRPC + REST) | ✅ | 🟡 REST only | 🟡 REST only | 🟡 REST only |
| SaaS + self-host parity | ✅ | ✅ | ➖ N/A | ➖ N/A |
ZITADEL Cloud and self-hosted ZITADEL run the same codebase.
Key differentiators for architects:
- Relational core, event-driven soul — every mutation is written as an immutable event for a complete, API-accessible audit trail. Unlike systems that log only select activities, ZITADEL provides a comprehensive event stream that can be audited or streamed to external systems via Webhooks.
- Strict multi-tenant hierarchy — Identity System → Organizations → Projects, with isolated data and policy scoping at multiple levels
- API-first design — every resource and action is available via connectRPC, gRPC, and HTTP/JSON APIs
- Zero-downtime updates and horizontal scalability without external session stores
Get Started in 3 Minutes
ZITADEL Self-Hosted
# Docker Compose — up and running in under 3 minutes
curl -LO https://raw.githubusercontent.com/zitadel/zitadel/main/deploy/compose/docker-compose.yml \
&& curl -LO https://raw.githubusercontent.com/zitadel/zitadel/main/deploy/compose/.env.example \
&& cp .env.example .env \
&& docker compose up -d --wait
Full deployment guides:
Need professional support for your self-hosted deployment? Contact us.
ZITADEL Cloud (SaaS)
Start for free at zitadel.com — no credit card required. Available in US · EU · AU · CH. Pay-as-you-go pricing.
Integrate with the V2 API
ZITADEL exposes every capability over a typed API. Here's how to create a user with the V2 REST API:
curl -X POST https://$ZITADEL_DOMAIN/v2/users/human \
-H "Authorization: Bearer $ACCESS_TOKEN" \
-H "Content-Type: application/json" \
-d '{
"username": "[email protected]",
"profile": { "givenName": "Alice", "familyName": "Smith" },
"email": { "email": "[email protected]", "sendCode": {} }
}'
Explore the full API reference — including connectRPC and gRPC transports — or jump straight to quickstart examples.
Features
Authentication
- Single Sign On (SSO) · Username/Password · Passkeys (FIDO2 / WebAuthn)
- MFA: OTP, U2F, OTP Email, OTP SMS
- LDAP · Enterprise IdPs and social logins
- OpenID Connect certified · SAML 2.0 · Device authorization
- Machine-to-machine: JWT Profile, PAT, Client Credentials
- Token exchange and impersonation
- Custom sessions for flows beyond OIDC/SAML
- Hosted Login V2
Multi-Tenancy
- Identity brokering with pre-built IdP templates
- Customizable B2B onboarding with self-service for customers
- Delegated role management to third parties
- Domain discovery
Integration
- gRPC, connectRPC, and REST APIs for every resource
- Actions: webhooks, custom code, token enrichment
- RBAC · SCIM 2.0 Server
- Audit log and SOC/SIEM integration
- SDKs and example apps
Self-Service & Admin
- Self-registration with email/phone verification
- Administration Console for orgs and projects
- Custom branding per organization
Deployment
- PostgreSQL (≥ 14) · Zero-downtime updates · High scalability
Track upcoming features on our roadmap and follow our changelog for recent updates.
Showcase
Login V2
Our new, fully customizable login experience — documentation
Adopters & Ecosystem
Used in production by organizations worldwide. See the full Adopters list — and add yours by submitting a pull request.
- SDKs: All supported languages and frameworks
- Examples: Clone and use our examples
How To Contribute
ZITADEL is built in the open and welcoming to contributions of all kinds.
- 📖 Read the Contribution Guide to get started
- 💬 Join the conversation on Discord
- 🐛 Report bugs or request features via GitHub Issues
Contributors
Made with contrib.rocks.
Security
Security policy: SECURITY.md
Vulnerability Disclosure Policy — how to responsibly report security issues.
Technical Advisories are published for major issues that could impact security or stability in production.
License
AGPL-3.0 — see LICENSING.md for the full licensing policy, including Apache 2.0 and MIT exceptions for specific directories.