CVE-2026-86466: Apache Airflow FAB provider: FAB Authentik provider: id_token issuer/audience not validated
Apache Airflow FAB provider: the Authentik OAuth path in the FAB auth manager does not validate the issuer or audience claims of the idtoken it accepts. An attacker holding a token that the same Authentik identity provider minted for a different client application can present it to Airflow and be authenticated as the user it names, because the audience claim is never checked. Affects deployments using the FAB auth manager with Authentik OAuth where the same Authentik instance also serves other applications; the attacker needs a valid token for any of those other applications, not for Airflow.
CVE-2026-75156 corrected the same missing validation on the Azure AD path in this file; the Authentik path was left unchanged and is fixed here. Deployments that applied the CVE-2026-75156 fix and use Authentik must also upgrade for this one.
Users of apache-airflow-providers-fab are recommended to upgrade to version 3.9.0 or later, which fixes the issue.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
apache-airflow-providers-fabto a version that resolves this vulnerability.Fixed in 3.9.0Patch CVE-2026-86466
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
Deployments using the FAB auth manager with Authentik OAuth are affected when the same Authentik instance also issues tokens for other client applications. An Authentik deployment used only for Airflow is not identified as affected by the provided information.
What must an attacker have to exploit it?
The attacker needs a valid token minted by the same Authentik identity provider for another client application. They do not need a token issued specifically for Airflow.
Does applying the earlier Azure AD-path fix address this problem?
No. CVE-2026-75156 corrected missing validation in the Azure AD path, while the Authentik path remained unchanged. Deployments using Authentik must upgrade for this issue even if they applied the earlier fix.
What version fixes the issue?
Upgrade apache-airflow-providers-fab to version 3.9.0 or later.