---
id: CVE-2026-102266
title: PyJWT is a Python implementation of JSON Web Token standards
summary: >-
  PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0
  until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification
  path used the decoded key without applying prepare_key validation. This occurs
  when a t…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-347
vendor: pyjwt_project
product: pyjwt
affected:
  - pyjwt = 2.13.0
patched:
  - PyJWT 2.14.0
published: '2026-09-28'
updated: '2026-10-07'
sourceUpdated: '2026-10-07T20:55:07.653'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-102266'
references:
  - url: >-
      https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c
    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-9j54-fg26-wv3r'
    label: security-advisories@github.com
  - url: 'https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-102266.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-102266'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2542671'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-102266'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-102266'
  - url: 'https://github.com/advisories/GHSA-9j54-fg26-wv3r'
  - url: 'https://github.com/jpadilla/pyjwt'
  - url: 'https://pypi.org/project/pyjwt'
  - url: 'https://access.redhat.com/errata/RHSA-2026:82415'
  - url: 'https://access.redhat.com/errata/RHSA-2026:82368'
  - url: 'https://access.redhat.com/errata/RHSA-2026:82061'
  - url: 'https://access.redhat.com/errata/RHSA-2026:82059'
  - url: 'https://access.redhat.com/errata/RHSA-2026:82371'
  - url: 'https://access.redhat.com/errata/RHSA-2026:87004'
  - url: 'https://access.redhat.com/errata/RHSA-2026:87120'
  - url: 'https://access.redhat.com/errata/RHSA-2026:87124'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
  - ghsa
  - pip
  - osv
epss: 0.00225
epssPercentile: 0.13255
aliases:
  - GHSA-9j54-fg26-wv3r
  - PYSEC-2026-4143
ecosystem: pip
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-29T19:28:36.086597Z'
ingestedAt: '2026-09-28T21:20:54.779Z'
---

## Overview

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded key without applying prepare_key validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As a result, an attacker signs an HMAC token with the same zero-length key accepted by PyJWT. Consequently, forged token can carry arbitrary authenticated claims. This issue is fixed in version 2.14.0.

## Affected

- `pyjwt = 2.13.0`

## Remediation

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

## Package advisory (CVE-2026-102266)

Affected packages:

- `PyJWT >= 2.13.0, < 2.14.0`

Patched in:

- `PyJWT 2.14.0`

Source: https://github.com/advisories/GHSA-9j54-fg26-wv3r

## Vendor advisories

- **Red Hat VEX** · Important · affected: Ansible Automation Orchestrator 2026, Fence Agents Remediation Operator, Migration Toolkit for Applications 8, Red Hat Ansible Automation Platform 2, Red Hat Ceph Storage 4, Red Hat Ceph Storage 7, … · no fix planned: Red Hat Ceph Storage 4, Red Hat Ceph Storage 7, Red Hat Ceph Storage 9, Ansible Automation Orchestrator 2026, … · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-102266.json)
- **RHSA-2026:82415** · Red Hat · fixed in: Red Hat AI Inference Server 3.5 · released 2026-10-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:82415)
- **RHSA-2026:82368** · Red Hat · fixed in: Red Hat AI Inference Server 3.5 · released 2026-10-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:82368)
- **RHSA-2026:82061** · Red Hat · fixed in: Red Hat AI Inference Server 3.5 · released 2026-10-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:82061)
- **RHSA-2026:82059** · Red Hat · fixed in: Red Hat AI Inference Server 3.5 · released 2026-10-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:82059)
- **RHSA-2026:82371** · Red Hat · fixed in: Red Hat AI Inference Server 3.5 · released 2026-10-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:82371)
- **RHSA-2026:87004** · Red Hat · fixed in: Red Hat Ansible Automation Platform 2.6 for RHEL 9 · released 2026-10-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:87004)
- **RHSA-2026:87120** · Red Hat · fixed in: Red Hat Ansible Automation Platform 2.6 · released 2026-10-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:87120)
- **RHSA-2026:87124** · Red Hat · fixed in: Red Hat Ansible Automation Platform 2.7 · released 2026-10-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:87124)