CVE-2026-102266
Published:September 28, 2026
Updated:October 07, 2026
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
pyjwt (CONDA):
Affected version(s) =2.13.0 <2.14.0Fix Suggestion:
Update to version 2.14.0https://github.com/jpadilla/pyjwt.git (GITHUB):
Affected version(s) =2.13.0 <2.14.0Fix Suggestion:
Update to version 2.14.0pyjwt (PYTHON):
Affected version(s) =2.13.0 <2.14.0Fix Suggestion:
Update to version 2.14.0Related Resources (8)
Do you need more information?
Contact UsCVSS v4
Base Score:
9.1
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.4
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Improper Verification of Cryptographic Signature
EPSS
Base Score:
0.18