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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy 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/f91ed44dd65baaf457f4b3353ed35e98a75393…
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-9j54-fg26-wv3r
security-advisories@github.com