CVE-2021-21239

Name	CVE-2021-21239
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. Users of pysaml2 that use the default CryptoBackendXmlSec1 backend and need to verify signed SAML documents are impacted. PySAML2 does not ensure that a signed SAML document is correctly signed. The default CryptoBackendXmlSec1 backend is using the xmlsec1 binary to verify the signature of signed SAML documents, but by default xmlsec1 accepts any type of key found within the given document. xmlsec1 needs to be configured explicitly to only use only _x509 certificates_ for the verification process of the SAML document signature. This is fixed in PySAML2 6.5.0.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-2577-1
Debian Bugs	980772

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
python-pysaml2 (PTS)	buster, buster (security)	4.5.0-4+deb10u1	vulnerable
	bullseye	6.5.1-1	fixed
	bookworm	7.0.1-2	fixed
	sid, trixie	7.4.2-4	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
python-pysaml2	source	stretch	3.0.0-5+deb9u2		DLA-2577-1
python-pysaml2	source	(unstable)	6.5.1-1			980772

Notes

[buster] - python-pysaml2 <no-dsa> (Minor issue)
https://github.com/IdentityPython/pysaml2/security/advisories/GHSA-5p3x-r448-pc62
https://github.com/IdentityPython/pysaml2/commit/751dbf50a51131b13d55989395f9b115045f9737