🛡️ CVE-2026-48523
🟡 CVSS 5.4 — Medium ✅ No Known Exploit NVD
5.4
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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.

Details

Severity Medium
CVSS Score 5.4
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-05-28
Updated 2026-06-15
Modified 2026-06-02
Fix URL N/A

Affected Packages

Software From version Fixed in
pyjwt 2.9.0 2.12.1
unknown — —

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