CVE-2026-48524 LOW

CVE-2026-48524: PyJWT: PyJWKClient unbounded JWKS endpoint requests via attacker-controlled kid values (DoS)

Vendor Jpadilla
Product pyjwt
Weakness CWE-460
Published May 28, 2026
Last update May 28, 2026
View on NVD All CVEs

CVSS base score

3.7/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

What the vulnerability does

01Description

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 attacker's control. This vulnerability is fixed in 2.13.0.

Key dates

02Disclosure timeline

May 28, 2026 CVE published
May 28, 2026 Record updated