Auth Bypass in FAB Auth Manager of apache-airflow-providers-fab <3.7.3
CVE-2026-59243 Published on July 29, 2026
Apache Airflow FAB provider: FAB auth manager: JWT signature verification disabled by default for Azure AD OAuth (`verify_signature` defaults to `False`)
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`.
Weakness Type
Improper Verification of Cryptographic Signature
The software does not verify, or incorrectly verifies, the cryptographic signature for data.
Products Associated with CVE-2026-59243
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Affected Versions
Apache Software Foundation Apache Airflow FAB provider:- Before 3.7.3 is affected.