CVE-2026-85394
python-jose through 3.5.0 Algorithm Confusion via DER-encoded Public Key as HMAC Secret
CVSS Score
9.1
EPSS Score
0.0%
EPSS Percentile
0th
python-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.
| CWE | CWE-347 |
| Vendor | mpdavis |
| Product | python-jose |
| Published | Sep 3, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
mpdavis / python-jose
0 ≤ 3.5.0
References
github.com: https://github.com/mpdavis/python-jose/issues/414 github.com: https://github.com/mpdavis/python-jose github.com: https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/backends/native.py github.com: https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/utils.py github.com: https://github.com/advisories/GHSA-6c5p-j8vq-pqhj vulncheck.com: https://www.vulncheck.com/advisories/python-jose-through-3.5.0-algorithm-confusion-via-der-encoded-public-key-as-hmac-secret
Credits
George Chen