---
id: CVE-2026-102268
title: PyJWT is a Python implementation of JSON Web Token standards
summary: >-
  PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0,
  is_pem_format in jwt/utils.py is affected because is_pem_format does not
  recognize every PEM representation accepted by the cryptography loader. This
  occurs w…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-347
vendor: jpadilla
product: pyjwt
affected:
  - pyjwt < 2.14.0
published: '2026-09-28'
updated: '2026-09-28'
sourceUpdated: '2026-09-28T21:17:14.600'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-102268'
references:
  - url: >-
      https://github.com/jpadilla/pyjwt/commit/8b4e233a22206b34ec1186e912e75c0b2396ac07
    label: security-advisories@github.com
  - url: 'https://github.com/jpadilla/pyjwt/releases/tag/2.14.0'
    label: security-advisories@github.com
  - url: 'https://github.com/jpadilla/pyjwt/security/advisories/GHSA-ffc3-869f-jxw9'
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-28T21:20:54.780Z'
---

## Overview

PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, is_pem_format in jwt/utils.py is affected because is_pem_format does not recognize every PEM representation accepted by the cryptography loader. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a mutated public-key PEM as raw key bytes. As a result, HMACAlgorithm.prepare_key treats the unrecognized asymmetric public key as an HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens. This issue is fixed in version 2.14.0.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.