Summary
ZITADEL: Missing Token Audience Validation (aud) in JWT IdP Provider
Full technical description
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.
Affected Versions
Systems running one of the following versions are affected:
- 4.x:
4.0.0through4.11.0(including RC versions) - 3.x:
3.0.0through3.4.11(including RC versions)
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:
- 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.
- 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
audfield 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.
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.
CVE-2026-55669 has a CVSS score of 4.2 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.80.0-v2.20.0.20260615132747-d184e976fc79); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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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.
Frequently Asked Questions
- What is CVE-2026-55669? CVE-2026-55669 is a medium-severity security vulnerability in github.com/zitadel/zitadel (go), affecting versions < 1.80.0-v2.20.0.20260615132747-d184e976fc79. It is fixed in 1.80.0-v2.20.0.20260615132747-d184e976fc79.
- How severe is CVE-2026-55669? CVE-2026-55669 has a CVSS score of 4.2 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/zitadel/zitadel are affected by CVE-2026-55669? github.com/zitadel/zitadel (go) versions < 1.80.0-v2.20.0.20260615132747-d184e976fc79 is affected.
- Is there a fix for CVE-2026-55669? Yes. CVE-2026-55669 is fixed in 1.80.0-v2.20.0.20260615132747-d184e976fc79. Upgrade to this version or later.
- Is CVE-2026-55669 exploitable, and should I be worried? Whether CVE-2026-55669 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-55669 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-55669? Upgrade
github.com/zitadel/zitadelto 1.80.0-v2.20.0.20260615132747-d184e976fc79 or later.