CVE-2021-21238

critical
Published 2021-01-21 · Modified 2023-11-08
CVSS v3
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
CVSS v2
VIR risk
9.5

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.

Predictions

Exploit likelihood
30%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-21238

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-21238.html

OS impact

OSVersionStatusFixed in
arch archfixed6.5.1-1
suse slesaffected
debian debianbookwormfixed6.5.1-1
debian debianbullseyefixed6.5.1-1
debian debianforkyfixed6.5.1-1
debian debiansidfixed6.5.1-1
debian debiantrixiefixed6.5.1-1

Package impact

EcosystemPackageVulnerableFixed
python PyPIpysaml2<6.5.06.5.0
python PyPIpysaml2<1d8fd268f5bf887480a403a7a5ef8f048157cc14||<6.5.01d8fd268f5bf887480a403a7a5ef8f048157cc14

References

Verify integrity in audit chain (admin only). AS-IS.