# CVE-2026-59243: Apache Airflow FAB provider authentication bypass in Azure AD OAuth

Source: https://junglewise.ai/threats/cve-2026-59243-apache-airflow-fab-provider-authentication-bypass-in-azure-ad  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-29. Updated: 2026-07-29  
License: CC BY 4.0 with a link back

CVE-2026-59243 · Severity: info · CVSS 8.1 · Published 2026-07-29

A security flaw in the Apache Airflow FAB provider allows unauthorized users to bypass login protections when using Azure AD for authentication. By providing a specially crafted or unsigned identity token, an attacker can log in as any user, including administrators. This could lead to full control over the Airflow environment and access to sensitive data or automated workflows.

Technologies: [Apache Software Foundation Airflow FAB Provider](https://junglewise.ai/threats/technologies/airflow-fab-provider). Vendors: [Apache Software Foundation](https://junglewise.ai/threats/vendors/apache-software-foundation).

## Quick answers

**Is CVE-2026-59243 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59243 being exploited in the wild.

**How severe is CVE-2026-59243?** Informational severity, with a CVSS score of 8.1, published 29 July 2026.

**Which products and versions are affected?** Apache Software Foundation Airflow FAB Provider < 3.7.3.

**Is there a fix for CVE-2026-59243?** A patch was published on 2026-07-07: Fix merged into main branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-59243 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-59243?** Check whether you run Apache Software Foundation Airflow FAB Provider at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The FAB (Flask-AppBuilder) auth manager in the Apache Airflow FAB provider incorrectly defaulted the `verify_signature` parameter to `False` during the Azure AD OAuth login flow. This vulnerability (CWE-347) allows a remote, unauthenticated attacker to present a forged ID token or an unsigned token using the 'alg:none' configuration to the OAuth callback endpoint. Because the signature is not validated against the Microsoft JWKS by default, the application accepts the identity claims within the token, enabling the attacker to impersonate any user, including those with administrative privileges. The issue is resolved in version 3.7.3, which changes the default behavior to `verify_signature=True`.

## Affected products

- Apache Software Foundation Apache Airflow FAB provider (apache-airflow-providers-fab) < 3.7.3

## Timeline

- 2026-07-04: other: Remediation pull request opened
- 2026-07-07: patched: Fix merged into main branch
- 2026-07-28: disclosed: Public disclosure via oss-security mailing list
- 2026-07-29: advisory: NVD publication date

## References

- [https://pypi.python.org/](https://pypi.python.org/)
- [https://github.com/apache/airflow/pull/69374](https://github.com/apache/airflow/pull/69374)
- [https://lists.apache.org/thread/x4784l7z00tl3gw4tv2dmvoon77rxgpl](https://lists.apache.org/thread/x4784l7z00tl3gw4tv2dmvoon77rxgpl)
- [http://www.openwall.com/lists/oss-security/2026/07/28/10](http://www.openwall.com/lists/oss-security/2026/07/28/10)

## Related threats

- [Apache Airflow FAB provider privilege escalation via DAG name collision](https://junglewise.ai/threats/cve-2026-59245-apache-airflow-fab-provider-privilege-escalation-via-dag-name)
- [Apache Airflow FAB Auth Manager LDAP filter injection](https://junglewise.ai/threats/cve-2026-46745-apache-airflow-fab-auth-manager-ldap-filter-injection)