Airflow Keycloak provider: credentials of any confidential client in the realm log into Airflow

Impact

The Keycloak auth manager's unauthenticated token endpoint accepts a client-credentials grant from any confidential client registered in the same Keycloak realm, not only Airflow's own client. Anyone holding credentials for an unrelated application that shares the realm - a monitoring tool, an internal service - gets a signed Airflow session token for that service account. On a fleet where Airflow drives data pipelines and GPU training jobs, that is unintended access to the scheduler's UI and API; what the intruder can then do is whatever that service account is authorized for, plus any endpoint gated only on being authenticated. The endpoint also answers unauthenticated credential guesses against Keycloak under Airflow's identity, which makes Airflow a password-spraying oracle for the realm.

Who can reach it

Anyone who can reach the Airflow web endpoint and holds valid credentials for any one confidential client in the shared Keycloak realm. No Airflow account and no prior Airflow authentication needed.

What to do

Upgrade apache-airflow-providers-keycloak to 0.10.0 or later, which accepts only the configured client on that grant; this is a provider package bump plus a restart of the API server / webserver components, no worker or node disruption. If the upgrade must wait, the exposure is limited by moving Airflow to a dedicated Keycloak realm with no other confidential clients.

References

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