CVE-2026-85394: Improper Verification of Cryptographic Signature in mpdavis python-jose
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.
CVE-2026-85394: Improper Verification of Cryptographic Signature in mpdavis python-jose
Description
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.
CVSS v4.0
Score 9.3critical
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-03T18:10:58.475Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a99c5a7acd9273b4957e1ed
Added to database: 09/03/2026, 19:08:23 UTC
Last updated: 09/03/2026, 19:52:30 UTC
Views: 5
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