CVE-2026-85394
CVE-2026-85394 · python-jose through 3.5.0 Algorithm Confusion via DER-encoded Public Key as HMAC Secret
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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 9.3 · Critical · EPSS 0.2%
- Published
- Updated
Stack: system
Affected products and versions
python-jose
- Versions
- ≥ 0, ≤ 3.5.0: Affected (semver)
No fix published
python-jose Ubuntu:22.04:LTS
- Versions
- 3.3.0+dfsg-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
python-jose Ubuntu:24.04:LTS
- Versions
- 3.3.0+dfsg-4
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
Original sources
- 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
- https://nvd.nist.gov/vuln/detail/CVE-2026-85394