CVE-2026-102272
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret. Consequently, an attacker who knows the public key can forge authenticated tokens. This issue is fixed in version 2.14.0.
Published:Sep 28, 2026
Last Modified:Oct 6, 2026
EPS:Sep 28, 2026
EPSS Score:0.00185
CVSS Score:7.4
Affected Products
Vendor
Product
Action
Vendor
Jpadilla
Product
Pyjwt
Jpadilla
Pyjwt
Vendor
Pyjwt Project
Product
Pyjwt
Pyjwt Project
Pyjwt
Exploits
Common Weakness Enumeration
Common Attack Pattern Enumeration and Classification (CAPEC)
Related CVEs
Common Vulnerability Scoring System
Attack Vector
Network
Adjacent
Local
Physical
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
