CVE-2026-85394: Mpdavis Python-Jose

Critical severity, CVSS 9.1. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Mpdavis Python-Jose: up to and including 3.5.0

Published 2026-09-03. Last modified 2026-09-24.