CRITICAL 9.1 NVD
CVE-2026-120459
python-jose through 3.5.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to forge JWTs because HMACKey and CryptographyHM
python-jose through 3.5.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to forge JWTs because HMACKey and CryptographyHMACKey accept zero-length HMAC secrets. When an application's HS256/HS384/HS512 verification key resolves to empty, such as an oct JWK with empty k, attackers can forge tokens with arbitrary claims that jwt.decode accepts.
References
- https://github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/cryptography_backend.py
- https://github.com/mpdavis/python-jose/blob/3.5.0/jose/backends/native.py
- https://github.com/mpdavis/python-jose/issues/398
- https://www.vulncheck.com/advisories/python-jose-through-3.5.0-authentication-bypass-via-e
This critical severity vulnerability with a CVSS score of 9.1 was published on 2026-11-02 via NVD.
Risk Timeline
CVE Disclosed2026-11-02 · -1 days ago
Remediation Resources
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