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PyJWT CVE-2026-48524

| EUVD-2026-32916 LOW
Improper Cleanup on Thrown Exception (CWE-460)
2026-05-28 GitHub_M
Python Information Disclosure
3.7
CVSS 3.1

CVSS VectorNVD

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

Lifecycle Timeline

2
Patch available
May 28, 2026 - 17:01 EUVD
Analysis Generated
May 28, 2026 - 15:55 vuln.today

DescriptionNVD

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.

AnalysisAI

Unconstrained outbound JWKS requests in PyJWT's PyJWKClient.get_signing_key() allow unauthenticated remote attackers to amplify HTTP traffic toward a downstream JWKS endpoint by submitting JWTs carrying arbitrary, unrecognized kid values. All PyJWT versions prior to 2.13.0 are affected when the PyJWKClient class is used for signature verification. …

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CVE-2026-48524 vulnerability details – vuln.today
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