CVE-2026-40861: Apache Airflow: Arbitrary File Read via Log Symlink following in FileTaskHandler

A Dag author could either (a) create a symlink under their task's log directory pointing to an arbitrary file readable by the API server process (read-path attack — e.g. /etc/passwd or airflow.cfg) or (b) supply a taskid containing .. sequences accepted by the Task SDK's KEYREGEX (write-path attack), and in both cases the FileTaskHandler resolves the log path outside the configured baselogfolder, leaking or overwriting arbitrary files. Only affects deployments where the worker log folder is shared with the API server. Users are advised to upgrade to apache-airflow 3.2.2 or later. As a defense-in-depth mitigation, deploy the worker and API server with separate log volumes so that worker-controlled paths cannot reach the API server's filesystem.