CVE-2026-102267

Received Received - Intake

PyJWKClient Redirect Validation Bypass in PyJWT

Publication date: 2026-09-28

Last updated on: 2026-09-28

Assigner: GitHub, Inc.

Description

PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT PyJWKClient is affected because redirect destinations are not revalidated against the JWKS trust boundary. This occurs when a configured trusted JWKS endpoint returns an attacker-influenced redirect. As a result, PyJWKClient follows the redirect and consumes the redirected response as key material. Consequently, forwarded credentials may be disclosed or verification keys may be substituted. This issue is fixed in version 2.14.0.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-09-28

Last Modified

2026-09-28

Generated

2026-09-29

AI Q&A

2026-09-29

EPSS Evaluated

N/A

NVD

CVE-2026-102267

Affected Vendors & Products

Vendor	Product	Version / Range
pyjwt	pyjwt	to 2.14.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-345	The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
CWE-200	The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
CWE-918	The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Attack-Flow Graph

Executive Summary

PyJWT before 2.14.0 has a vulnerability in PyJWKClient where redirect destinations are not revalidated against the JWKS trust boundary. If a trusted JWKS endpoint returns a malicious redirect, PyJWKClient follows it and uses the redirected response as key material. This can lead to credential disclosure or key substitution.

Detection Guidance

Check PyJWT version with pip show PyJWT. If version is below 2.14.0, the system is vulnerable. Inspect network traffic for unexpected redirects to untrusted JWKS endpoints.

Impact Analysis

An attacker could exploit this to intercept credentials or replace verification keys, potentially gaining unauthorized access to systems relying on JWT validation. This could lead to data breaches or impersonation attacks.

Compliance Impact

This vulnerability could violate GDPR by exposing personal data or HIPAA by compromising protected health information, as unauthorized access may occur. Compliance requires ensuring JWT validation integrity to protect sensitive data.

Mitigation Strategies

Upgrade PyJWT to version 2.14.0 or later immediately. Review JWKS endpoint configurations to ensure redirects are validated against the trust boundary.

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