GHSA-29fc-p6c4-24cg
Fix: symfony/symfony@6b717aaGHSA-29fc-p6c4-24cg is a CWE-345 vulnerability in symfony/security-http. O3 Security confirms whether GHSA-29fc-p6c4-24cg is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Symfony's OidcTokenHandler Accepts JWTs Missing aud/iss/exp Claims
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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 GHSA-29fc-p6c4-24cg.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
symfony/security-http🐘symfony/security-http🐘symfony/security-http🐘symfony/symfony🐘symfony/symfony🐘symfony/symfonyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Description
OidcTokenHandler is Symfony's built-in access-token handler for OpenID Connect: it validates a bearer JWT and returns the authenticated user identity. It delegates claim validation to the web-token/jwt-checker library's ClaimCheckerManager.
OidcTokenHandler::verifyClaims() registers audience (aud), issuer (iss), and expiry (exp) checkers, but never passes the $mandatoryClaims argument to ClaimCheckerManager::check(). That method only validates claims that are present in the token: a checker for an absent claim is silently skipped. A validly-signed JWT that simply omits aud, iss, and exp therefore passes verification.
Resolution
The OidcTokenHandler now calls the ClaimCheckerManager with the list of mandatory claims so that tokens missing aud, iss, or exp are rejected.
The patch for this issue is available here for branch 6.4.
Credits
Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/security-http | ≥ 6.3.0&&< 6.4.40 | 6.4.40 |
| 🐘Packagist | symfony/security-http | ≥ 7.4.0&&< 7.4.12 | 7.4.12 |
| 🐘Packagist | symfony/security-http | ≥ 8.0.0&&< 8.0.12 | 8.0.12 |
| 🐘Packagist | symfony/symfony | ≥ 6.3.0&&< 6.4.40 | 6.4.40 |
| 🐘Packagist | symfony/symfony | ≥ 7.4.0&&< 7.4.12 | 7.4.12 |
| 🐘Packagist | symfony/symfony | ≥ 8.0.0&&< 8.0.12 | 8.0.12 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/security-http. 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.
Fix
Update symfony/security-http to 6.4.40 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-29fc-p6c4-24cg is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-29fc-p6c4-24cg 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-29fc-p6c4-24cg. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-29fc-p6c4-24cg in your dependencies?
O3 detects GHSA-29fc-p6c4-24cg across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.