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GHSA-g5h5-m4hm-xjrr

MEDIUM

GHSA-g5h5-m4hm-xjrr is a medium-severity (CVSS 4.2) CWE-346 vulnerability in github.com/zitadel/zitadel. O3 Security confirms whether GHSA-g5h5-m4hm-xjrr is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

ZITADEL: Missing Token Audience Validation (`aud`) in JWT IdP Provider

Also known asCVE-2026-55669GO-2026-5391
Published
Jun 18, 2026
Updated
Jun 25, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

Blast Radius

1 pkg affected
🐹github.com/zitadel/zitadel

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

An authentication bypass vulnerability was discovered in ZITADEL's external JWT Identity Provider (IdP) implementation.

When validating JSON Web Tokens (JWTs) from an external provider, ZITADEL properly checks the token's cryptographic signature and issuer (iss), but it fails to validate the audience (aud) claim.

As a result, any validly signed token from the trusted issuer will be accepted. An attacker who is a legitimate user of a completely separate service sharing the same enterprise Identity Provider can intercept or present their token for that service to ZITADEL, successfully authenticating as that user without authorization.

Impact

In a controlled enterprise environment where Identity Providers are explicitly managed, the operational risk is localized. Exploitation requires that an attacker already possesses a valid standard user session token from a shared, trusted issuer intended for an entirely different relying party, limiting the vector to specific, rare cross-service setups where trust boundaries overlap.

Affected Versions

Systems running one of the following versions are affected:

  • 4.x: 4.0.0 through 4.11.0 (including RC versions)
  • 3.x: 3.0.0 through 3.4.11 (including RC versions)

Patches

The vulnerability has been addressed in the latest releases, where a required audience can be set in the IdP configuration. Once provided, audience validation will be enforced.

Workarounds

The recommended solution is to update ZITADEL to a patched version.

If an immediate upgrade is not possible, you can mitigate the risk at the infrastructure layer:

  1. At the IdP: Ensure the external Identity Provider issues scoped tokens with highly unique, non-overlapping audience values that cannot be misconstrued by separate service deployments.
  2. At the Perimeter: Deploy a reverse proxy, API gateway, or Web Application Firewall (WAF) layer in front of ZITADEL to inspect incoming identity tokens and explicitly drop requests where the aud field does not strictly match ZITADEL's deployment target.

Questions

If you have any questions or comments about this advisory, please email us at [email protected]

Credits

Thanks to Android-Login-Analysis, Jason Zhou and Pedro Giglioti for reporting this vulnerability.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/zitadel/zitadelall versions1.80.0-v2.20.0.20260615132747-d184e976fc79

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zitadel/zitadel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update github.com/zitadel/zitadel to 1.80.0-v2.20.0.20260615132747-d184e976fc79 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g5h5-m4hm-xjrr is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-g5h5-m4hm-xjrr is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-g5h5-m4hm-xjrr. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary An authentication bypass vulnerability was discovered in ZITADEL's external JWT Identity Provider (IdP) implementation. When validating JSON Web Tokens (JWTs) from an external provider, ZITADEL properly checks the token's cryptographic signature and issuer (`iss`), but it fails to validate the audience (`aud`) claim. As a result, any validly signed token from the trusted issuer will be accepted. An attacker who is a legitimate user of a completely separate service sharing the same enterprise Identity Provider can intercept or present their token for that service to ZITADEL, succ
O3 Security · Impact-Aware SCA

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