PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient.get_signing_key() forces a fresh HTTP request to the JWKS endpoint for every JWT with an unknown kid value, with no rate limiting. Since kid comes from the unverified token header, an attacker can trigger unlimited outbound requests. The vulnerability surfaces only when a JWKS fetch fails; an attacker can attempt to provoke that with sustained unknown-kid traffic, but the outcome depends on upstream JWKS-endpoint behavior (rate limiting, transient errors) which is beyond the attackers control. This vulnerability is fixed in 2.13.0.
Weakness
The product does not clean up its state or incorrectly cleans up its state when an exception is thrown, leading to unexpected state or control flow.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Pyjwt | Pyjwt_project | * | 2.13.0 (excluding) |