GHSA-m2wj-r6g3-fxfx
MEDIUMSymfony possible session fixation vulnerability
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.
Blast Radius
symfony/security-http🐘symfony/security-http🐘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
SessionStrategyListener does not always migrate the session after a successful login. It only migrate the session when the logged-in user identifier changes. In some use cases, the user identifier doesn't change between the verification phase and the successful login, while the token itself changes from one type (partially-authenticated) to another (fully-authenticated). When this happens, the session id should be regenerated to prevent possible session fixations.
Resolution
Symfony now checks the type of the token in addition to the user identifier before deciding whether the session id should be regenerated.
The patch for this issue is available here for branch 5.4.
Credits
We would like to thank Robert Meijers for reporting the issue and providing the fix.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/security-http | ≥ 5.4.21&&< 5.4.31 | 5.4.31 |
| 🐘Packagist | symfony/security-http | ≥ 6.2.7&&< 6.3.8 | 6.3.8 |
| 🐘Packagist | symfony/symfony | ≥ 5.4.21&&< 5.4.31 | 5.4.31 |
| 🐘Packagist | symfony/symfony | ≥ 6.2.7&&< 6.3.8 | 6.3.8 |
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 5.4.31 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m2wj-r6g3-fxfx 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-m2wj-r6g3-fxfx 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-m2wj-r6g3-fxfx. 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-m2wj-r6g3-fxfx in your dependencies?
O3 detects GHSA-m2wj-r6g3-fxfx across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.