How severe is CVE-2026-56664?

CVE-2026-56664 has a CVSS score of 4.2/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-56664?

CVE-2026-56664 affects the following packages: github.com/zitadel/zitadel (Go). Ecosystems affected: Go.

How do I fix CVE-2026-56664?

Update github.com/zitadel/zitadel to 1.80.0-v2.20.0.20260615122908-fad02c6d9f45 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-56664 is resolved across your whole dependency graph.

How do I detect CVE-2026-56664 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zitadel/zitadel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-56664 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-56664 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-56664 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-56664?

CVE-2026-56664 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 25th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-56664?

CVE-2026-56664 is classified as CWE-613 (CWE-613). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-56664 published, and has it been updated?

CVE-2026-56664 was published on July 10, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2026-56664 — zitadel

MEDIUMFix: zitadel/zitadel@4925fab

CVE-2026-56664 is a medium-severity (CVSS 4.2) CWE-613 vulnerability in github.com/zitadel/zitadel. A fix is available for github.com/zitadel/zitadel — see the affected versions and patch details below.

ZITADEL: Missing Token Lifecyle Validation (`exp` and `iat`) in JWT IdP Provider

Also known asGHSA-wxg7-w2v3-w38gGO-2026-5732

Published

Jul 10, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 28, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-56664.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs25th percentile — riskier than 25% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-56664 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 397,508 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

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

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
3.x: Upgrade to $\ge$ 3.4.12

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

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

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/zitadel/zitadel`	all versions	1.80.0-v2.20.0.20260615122908-fad02c6d9f45`go get github.com/zitadel/zitadel@v1.80.0-v2.20.0.20260615122908-fad02c6d9f45`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zitadel/zitadel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/zitadel/zitadel to 1.80.0-v2.20.0.20260615122908-fad02c6d9f45 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-56664 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### 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. ZITADE