CVE-2021-21238Medium· 6.5▾ SunlitSAML XML Signature wrapping in PySAML2
▾ Sunlit zone — Low / medium · no exploitation signal
impact 35.8 · likelihood 0.2 · exploitation 0
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Exploit-prediction probability, daily snapshots since Sep 12.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
1.1%
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.
Users should upgrade to pysaml2 v6.5.0.
No workaround provided at this point.
No references provided at this point.
If you have any questions or comments about this advisory:
pysaml2 < 6.5.0Upgrade to a patched release:
pysaml2 6.5.0Connected by shared product, vendor, weakness, or advisory.