GitHub Advisoryadvisory · PyPI
GHSA-3qf3-8w2g-rqmx python-jose algorithm confusion guard bypassed by DER-encoded public keys
CRITICAL
Official page ↗
- Aliases
- CVE-2026-85394
- Ecosystem
- PyPI
- Packages
- python-jose
- Severity
- Critical
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- Weaknesses
- CWE-347
- Reviewed
- 2026-10-05
Affected packages
• PyPI python-jose: <= 3.5.0 (no fix yet)
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.
Related
Alias · CVE (1)
- CVE-2026-85394 python-jose through 3.5.0 fails to properly validate asymmetric keys in HMAC initialization, accepting DER-encoded public keys that lack… vulnerability
Weakness · CWE (1)
- CWE-347 Improper Verification of Cryptographic Signature weakness
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-85394 advisory
- https://github.com/mpdavis/python-jose/issues/414 web
- https://github.com/advisories/GHSA-6c5p-j8vq-pqhj advisory
- https://github.com/mpdavis/python-jose package
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/backends/native.py web
- https://github.com/mpdavis/python-jose/blob/018b310ddb8b50dcfd09a0c152117835a21dd656/jose/utils.py web
- https://www.vulncheck.com/advisories/python-jose-through-3.5.0-algorithm-confusion-via-der-encoded-public-key-as-hmac-secret web