CVE-2026-102265

PyJWT: Uncaught RecursionError in jwt.decode() on deeply nested token header

CVE-2026-102265 is fixed in pyjwt on 1 platform by DEBIAN-CVE-2026-102265 (version 2.14.0-1), released October 4, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine

CVSS

5.3

Moderate

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0034

28th percentile

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWS._load in jwt/api_jws.py is affected because parser catches ValueError but not RecursionError. This occurs when a deeply nested token header reaches json.loads. As a result, RecursionError escapes the documented PyJWT error hierarchy. Consequently, an unauthenticated malformed token can cause a request-level failure and HTTP 500. This issue is fixed in version 2.14.0.

Where it's fixed

Product	Fixed in	Fix	Released
Linux
pyjwt · Debian 14	2.14.0-1	DEBIAN-CVE-2026-102265	Oct 4, 2026

Details

Published
September 28, 2026
Weakness
Uncontrolled Recursion
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-102265

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