CVE-2021-21238
PySAML2 before 6.5.0 has an improper verification of cryptographic signature vulnerability.
Does this matter?
Lower severity and a low EPSS score (1.10%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
- EPSS
- 1.10% probability · 65th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-347
- Affected
- pysaml2 project/pysaml2
- Source
- security-advisories@github.com
EPSS 1.1% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/IdentityPython/pysaml2/commit/1d8fd268f5bf887480a403a7a5ef8f048157cc14Patch, Third Party Advisory
- https://github.com/IdentityPython/pysaml2/releases/tag/v6.5.0Third Party Advisory
- https://github.com/IdentityPython/pysaml2/security/advisories/GHSA-f4g9-h89h-jgv9Third Party Advisory
- https://pypi.org/project/pysaml2Product, Third Party Advisory
- https://github.com/IdentityPython/pysaml2/commit/1d8fd268f5bf887480a403a7a5ef8f048157cc14Patch, Third Party Advisory
- https://github.com/IdentityPython/pysaml2/releases/tag/v6.5.0Third Party Advisory
- https://github.com/IdentityPython/pysaml2/security/advisories/GHSA-f4g9-h89h-jgv9Third Party Advisory
- https://pypi.org/project/pysaml2Product, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.