CVE-2026-120459 python-jose through 3.5.0 Authentication Bypass via Empty HMAC Key
CriticalCVSS 9.1
EPSS 0.25%
- Published
- Updated
- Exploit status
- No public exploit known
Description
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.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| pypi python-jose | <= 3.5.0 | No fix listed |
| debian/python-jose(Debian:12) | All versions | No fix listed |
| debian/python-jose(Debian:12) | = 3.3.0+dfsg-4 | No fix listed |
| debian/python-jose(Debian:12) | = 3.3.0+dfsg-5 | No fix listed |
| ubuntu/python-jose(Ubuntu:22.04) | All versions | No fix listed |
| ubuntu/python-jose(Ubuntu:24.04) | All versions | No fix listed |
References
- github.com issue-tracking
- github.com technical-description
- github.com technical-description
- VulnCheck Advisory: python-jose through 3.5.0 Authentication Bypass via Empty HMAC Key third-party-advisory
- Debian Security Tracker CVE-2026-120459 vendor-advisory
- Ubuntu CVE tracker vendor-advisory
- www.cve.org