SAML XML Signature wrapping in PySAML2

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