CVE-2021-21238

Publication date 21 January 2021

Last updated 26 August 2025

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
python-pysaml2	25.10 questing	Not affected
	25.04 plucky	Not affected
	24.10 oracular	Not affected
	24.04 LTS noble	Not affected
	23.10 mantic	Not affected
	23.04 lunar	Not affected
	22.10 kinetic	Ignored end of life, was needed
	22.04 LTS jammy	Vulnerable
	21.10 impish	Ignored end of life
	21.04 hirsute	Ignored end of life
	20.10 groovy	Ignored end of life
	20.04 LTS focal	Vulnerable
	18.04 LTS bionic	Vulnerable
	16.04 LTS xenial	Vulnerable
	14.04 LTS trusty	Not in release

Notes

mdeslaur

Fixing this requires the python-xmlschema package, which is only available on hirsute. Backporting this fix to stable releases is intrusive and may introduce regressions.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
python-pysaml2	Upstream: 1d8fd26 Upstream: 3b70772

Severity score breakdown

Parameter	Value
Base score	6.5 · Medium
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Unchanged
Confidentiality	None
Integrity impact	High
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N