What’s Vulnerable › Vulnerabilities

CVE-2021-21238: SAML XML Signature wrapping

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-01-21 · updated 2026-06-17
• Weakness: CWE-347

Description

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

• IdentityPython pysaml2: before 6.5.0 — fixed in 6.5.0

How to fix

Upgrade to a fixed version: IdentityPython pysaml2 6.5.0. Check the vendor advisory for mitigations.

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
• 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

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