CVE-2026-85394
python-jose through 3.5.0 Algorithm Confusion via DER-encoded Public Key as HMAC Secret
CVSS 4.0 9.3 CRITICALCVSS 3.1 9.1 CRITICALCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-85394
Publishedpython-jose through 3.5.0 fails to properly validate asymmetric keys in HMAC initialization, accepting DER-encoded public keys that lack PEM armor or SSH prefixes. Attackers holding the service's public key can forge HS256 tokens that pass verification when algorithms are not explicitly restricted. This is an incomplete fix for CVE-2024-33663.
Read the publisher's advisoryAffected versions, risk and source history
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CVE-2026-85394 · CVE overview and exploitation status
cve-program · CVE-2026-85394
- https://github.com/mpdavis/python-jose/issues/414
- https://github.com/mpdavis/python-jose
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/backends/native.py
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/utils.py
- https://github.com/advisories/GHSA-6c5p-j8vq-pqhj
- https://www.vulncheck.com/advisories/python-jose-through-3.5.0-algorithm-confusion-via-der-encoded-public-key-as-hmac-secret
Related changes
Linked by CVE identifierNo related changes are available here.