---
id: CVE-2026-59243
title: >-
  The FAB auth manager's Azure AD OAuth login defaulted `verify_signature=False`
  when decoding the ID token, so an attacker able to present a forged or
  unsigned (`alg:none`) ID token to the OAuth callback could bypass
  authentication and lo…
summary: >-
  The FAB auth manager's Azure AD OAuth login defaulted `verify_signature=False`
  when decoding the ID token, so an attacker able to present a forged or
  unsigned (`alg:none`) ID token to the OAuth callback could bypass
  authentication and lo…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-347
vendor: apache
product: apache-airflow-providers-fab
affected:
  - apache-airflow-providers-fab < 3.7.3
patched:
  - apache-airflow-providers-fab 3.7.3
published: '2026-07-29'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T15:17:39.093'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-59243'
references:
  - url: 'https://github.com/apache/airflow/pull/69374'
    label: security@apache.org
  - url: 'https://lists.apache.org/thread/x4784l7z00tl3gw4tv2dmvoon77rxgpl'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/07/28/10'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
  - exploit-available
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-07-29T15:29:52.670228Z'
epss: 0.00445
epssPercentile: 0.38125
exploits:
  github: 2
  githubRepos:
    - 'https://github.com/MalHyuk/CVE-2026-59243'
    - 'https://github.com/0xdak/CVE-2026-59243_exploit'
  checkedAt: '2026-09-24T07:53:10.257Z'
exploitAvailable: true
ingestedAt: '2026-09-08T17:06:31.890Z'
---

## Overview

The FAB auth manager's Azure AD OAuth login defaulted `verify_signature=False` when decoding the ID token, so an attacker able to present a forged or unsigned (`alg:none`) ID token to the OAuth callback could bypass authentication and log in as an arbitrary user, including one holding the Admin role (CWE-347). Deployments running the FAB auth manager with the Azure AD OAuth login path under its default configuration are affected; the Authentik path already defaulted to `True`. This issue affects `apache-airflow-providers-fab` before 3.7.3. Users are advised to upgrade to `apache-airflow-providers-fab` 3.7.3, which defaults `verify_signature=True`.

## Affected

- `apache-airflow-providers-fab < 3.7.3`

## Remediation

Upgrade past the affected range:

- `apache-airflow-providers-fab 3.7.3`