CVE-2021-21238: PYSAML2 Project PYSAML2

Medium severity, CVSS 6.5. EPSS: 1.1% chance of exploitation in the next 30 days.

PySAML2 is a pure python implementation of SAML Version 2 Standard. PySAML2 before 6.5.0 has an improper verification of cryptographic signature vulnerability. All users of pysaml2 that need to validate signed SAML documents are impacted. The vulnerability is a variant of XML Signature wrapping because it did not validate the SAML document against an XML schema. This allowed invalid XML documents to be processed and such a document can trick pysaml2 with a wrapped signature. This is fixed in PySAML2 6.5.0.

Affected products

• PYSAML2 Project PYSAML2: before 6.5.0 (fixed in 6.5.0)

Published 2021-01-21. Last modified 2026-06-17.