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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Arch Fixed 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Fixed | 6.5.1-1 |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 6.5.1-1 |
| sid | Fixed | 6.5.1-1 |
| forky | Fixed | 6.5.1-1 |
| bullseye | Fixed | 6.5.1-1 |
| bookworm | Fixed | 6.5.1-1 |
References
- https://github.com/IdentityPython/pysaml2/security/advisories/GHSA-5p3x-r448-pc62
- https://nvd.nist.gov/vuln/detail/CVE-2021-21239
- https://github.com/IdentityPython/pysaml2/commit/46578df0695269a16f1c94171f1429873f90ed99
- https://github.com/IdentityPython/pysaml2
- https://github.com/IdentityPython/pysaml2/releases/tag/v6.5.0
- https://github.com/pypa/advisory-database/tree/main/vulns/pysaml2/PYSEC-2021-49.yaml
- https://lists.debian.org/debian-lts-announce/2021/02/msg00038.html
- https://pypi.org/project/pysaml2
- https://www.aleksey.com/pipermail/xmlsec/2013/009717.html
- https://www.suse.com/security/cve/CVE-2021-21239.html
- https://security-tracker.debian.org/tracker/CVE-2021-21239
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.