CVE-2026-56664

### Summary A token lifecycle validation vulnerability was discovered in ZITADEL's external JWT Identity Provider (IdP) implementation. ZITADEL enforces a 1-hour maximum token age freshness window (`maxAge`) calculated from the token's issue time. However, this safety check is guarded by a presence condition. If an incoming token omits the `iat` claim, the freshness check is entirely bypassed, allowing arbitrarily old tokens to pass authentication successfully. Per the OIDC Core 1.0 specification, identity token validation pipelines must strictly handle and enforce session expiration. ZITADEL's silent acceptance of tokens missing these temporal constraints compromises session integrity. ### Impact An attacker in possession of a stale token lacking an `iat` claim can reuse it indefinitely without triggering the maximum age freshness invalidation. ### Affected Versions Systems running one of the following versions are affected: * **4.x**: `4.0.0` through `4.15.1` (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. ZITADEL now explicitly rejects tokens that lack an `iat` claim. * **4.x**: Upgrade to $\ge$ [4.15.2](https://github.com/zitadel/zitadel/releases/tag/v4.15.2) * **3.x**: Upgrade to $\ge$ [3.4.12](https://github.com/zitadel/zitadel/releases/tag/v3.4.12) ### Workarounds The recommended solution is to update ZITADEL to a patched version. If an immediate upgrade is not feasible, ensure at the upstream Identity Provider level that your external IdP explicitly includes the `iat` claim in all signed JWTs. ### Publication Note This advisory covers a subset of the security issues originally published on ZITADEL's registry under this tracking ID. To adhere strictly to CVE formatting standards regarding independently fixable flaws, the original "Token Lifecycle Validation" disclosure has been split into two granular entries. This entry specifically tracks the missing `iat` claim logic, while a separate companion entry tracks the missing `exp` claim logic: [GHSA-v77h-2w3m-94hx](https://github.com/zitadel/zitadel/security/advisories/GHSA-v77h-2w3m-94hx) ### Questions If you have any questions or comments about this advisory, please email us at [security@zitadel.com](mailto:security@zitadel.com) ### Credits Thanks to [Android-Login-Analysis](https://github.com/Android-Login-Analysis), Jason Zhou and [Pedro Giglioti](https://github.com/Punisher100) for reporting this vulnerability.

ZITADEL: Missing Token Lifecyle Validation (`exp` and `iat`) in JWT IdP Provider in github.com/zitadel/zitadel