CVE-2026-102266
High · 7.4CVSS
7.4
EPSS
0.2%
Published
Sep 28, 2026
CISA due date
—
The record
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded key without applying prepare_key validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As a result, an attacker signs an HMAC token with the same zero-length key accepted by PyJWT. Consequently, forged token can carry arbitrary authenticated claims. This issue is fixed in version 2.14.0.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
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