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.
History

Thu, 28 May 2026 15:30:00 +0000

Type Values Removed Values Added
Description 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.
Title PyJWT: PyJWKClient unbounded JWKS endpoint requests via attacker-controlled kid values (DoS)
Weaknesses CWE-460
CWE-755
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-28T15:07:35.162Z

Reserved: 2026-05-21T16:18:10.619Z

Link: CVE-2026-48524

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-28T16:16:29.403

Modified: 2026-05-28T16:16:29.403

Link: CVE-2026-48524

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.