# 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.

- Web page: https://patchblox.com/security/cve/CVE-2026-102265
- Priority: Routine
- CVSS: 5.3 (Moderate)
- EPSS: 0.0034
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 28, 2026
- Weakness: Uncontrolled Recursion
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-102265

## Description

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

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | pyjwt Debian 14 | 2.14.0-1 | [DEBIAN-CVE-2026-102265](https://patchblox.com/security/data/fix/linux/debian-cve-2026-102265.md) | Oct 4, 2026 |

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Data as of 2026-11-09T19:38:12Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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