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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 1
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Pyjwt_Project Pyjwt
cpe:2.3:a:pyjwt_project:pyjwt:2.13.0:*:*:*:*:*:*:*
|
— | — |
References 3
https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f29560572…
security-advisories@github.com
https://github.com/jpadilla/pyjwt/releases/tag/2.14.0
security-advisories@github.com
https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947
security-advisories@github.com