What’s Vulnerable › Vulnerabilities
CVE-2026-48524: PyJWT: PyJWKClient unbounded JWKS endpoint requests via attacker-controlled kid values (DoS)
- Severity: low (CVSS 3.7 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-05-28 · updated 2026-10-26
- Weakness: CWE-460
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.
Affected products
- jpadilla pyjwt: before 2.13.0 — fixed in 2.13.0
How to fix
Upgrade to a fixed version: jpadilla pyjwt 2.13.0. Check the vendor advisory for mitigations.
References
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