GHSA-f4g9-h89h-jgv9
MEDIUMGHSA-f4g9-h89h-jgv9 is a medium-severity (CVSS 6.5) CWE-347 vulnerability in pysaml2. O3 Security confirms whether GHSA-f4g9-h89h-jgv9 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
SAML XML Signature wrapping in PySAML2
Blast Radius
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Description
Impact
All users of pysaml2 that use the default CryptoBackendXmlSec1 backend and need to verify signed SAML documents are impacted. pysaml2 <= 6.4.1 does not validate the SAML document against an XML schema. This allows invalid XML documents to trick the verification process, by presenting elements with a valid signature inside elements whose content has been malformed. The verification is offloaded to xmlsec1 and xmlsec1 will not validate every signature in the given document, but only the first it finds in the given scope.
Patches
Users should upgrade to pysaml2 v6.5.0.
Workarounds
No workaround provided at this point.
References
No references provided at this point.
Credits
- Victor Schönfelder Garcia (isits AG International School of IT Security)
- Juraj Somorovsky (Paderborn University)
- Vladislav Mladenov (Ruhr University Bochum)
For more information
If you have any questions or comments about this advisory:
- Open an issue in pysaml2
- Email us at the incident-response address
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pysaml2 | all versions | 6.5.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pysaml2. 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 pysaml2 to 6.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f4g9-h89h-jgv9 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-f4g9-h89h-jgv9 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-f4g9-h89h-jgv9. 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-f4g9-h89h-jgv9 in your dependencies?
O3 detects GHSA-f4g9-h89h-jgv9 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.