CVE-2026-48524

Low

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.

SeverityLow

CVSS3.7

Exploit probability—

ProductPyjwt

PublishedMay 28, 2026

First seenMay 28, 2026

Weakness typeCWE-460CWE-460 CWE-755CWE-755

How to fix

Update

pyjwt_project pyjwt2.13.0 or later
pyjwt2.13.0 or later

Affected products

Product	Affected versions	Fixed in
pyjwt_project pyjwt	v < 2.13.0	2.13.0
pyjwtPyPI	2.0.0 ≤ v < 2.13.0, v < 2.13.0	2.13.0

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