SB2021012135 - Improper Verification of Cryptographic Signature in Python implementation of SAML2

Description

This security bulletin contains information about 1 security vulnerability.

1) Improper Verification of Cryptographic Signature (CVE-ID: CVE-2021-21238)

The vulnerability allows a remote non-authenticated attacker to manipulate data.

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.

Remediation

Install update from vendor's website.

References

• https://github.com/IdentityPython/pysaml2/commit/1d8fd268f5bf887480a403a7a5ef8f048157cc14
• https://github.com/IdentityPython/pysaml2/releases/tag/v6.5.0
• https://github.com/IdentityPython/pysaml2/security/advisories/GHSA-f4g9-h89h-jgv9
• https://pypi.org/project/pysaml2