Apache Airflow's CeleryExecutor ran callback workloads (`ExecuteCallback`, used for deadline-alert callbacks) without validating the workload's authentication token. Anyone able to write to the Celery broker could enqueue a forged callback and execute arbitrary code on every CeleryExecutor worker, without Airflow credentials. Deployments using the CeleryExecutor are affected. Users are advised to upgrade to apache-airflow 3.4.0 or later, in which the worker claims the callback through the Execution API, validating the token, before running it.