CVE-2026-48523
CVE-2026-48523 · PyJWT: Algorithm allow-list bypass when decoding with `PyJWK` / `PyJWKClient` keys
This page contains facts from public vulnerability sources. Check the original advisory before updating.
PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode() or jwt.decode_complete() are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature verification is performed with the algorithm bound to the PyJWK object instead of the header algorithm. An attacker who controls a registered JWK/JWKS private key can sign with a disallowed algorithm, advertise an allowed algorithm in the JWT header, and still be accepted. The issue affects the documented PyJWKClient.get_signing_key_from_jwt(...) flow. This vulnerability is fixed in 2.13.0.
CVSS 5.4 · Medium · EPSS 0.2% · Fix available
- Published
- Updated
Affected products and versions
pyjwt
- Versions
- >= 2.9.0, < 2.13.0: Affected
No fix published
pyjwt Debian:13
- Versions
- 2.10.1-2
- 2.10.1-2+deb13u1
- 2.10.1-3
- 2.10.1-4
- 2.11.0-2
- 2.12.1-1
- 2.13.0-1
- 2.14.0-1
- 2.15.0-1
- 2.15.1-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
pyjwt Debian:14
- Versions
- 2.10.1-2
- 2.10.1-3
- 2.10.1-4
- 2.11.0-2
- 2.12.1-1
- Affected ranges
- ECOSYSTEM: < 2.13.0-1
Update to 2.13.0-1
pyjwt PyPI
- Versions
- 2.10.0
- 2.10.1
- 2.11.0
- 2.12.0
- 2.12.1
- 2.9.0
- Affected ranges
- ECOSYSTEM: ≥ 2.9.0, < 2.13.0
Update to 2.13.0
pyjwt PyPI
- Versions
- 2.10.0
- 2.10.1
- 2.11.0
- 2.12.0
- 2.9.0
- Affected ranges
- ECOSYSTEM: ≥ 2.9.0, < 2.12.1
Update to 2.12.1
pyjwt Ubuntu:25.10
- Versions
- 2.10.1-2
- 2.10.1-2ubuntu0.1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
pyjwt Ubuntu:26.04:LTS
- Versions
- 2.10.1-2
- 2.10.1-3
- 2.10.1-3build1
- 2.10.1-4
- 2.10.1-4ubuntu1
- Affected ranges
- ECOSYSTEM: < 2.10.1-4ubuntu1.1
Update to 2.10.1-4ubuntu1.1