CVE-2026-42359 Apache Airflow: Authenticated RCE via XCom PATCH endpoint — XComUpdateBody missing FORBIDDEN_XCOM_KEYS validator

A bug in Apache Airflow's XCom PATCH endpoint PATCH /api/v2/xcomEntries/key allowed an authenticated UI/API user with XCom write permission on a Dag to set XCom entries under reserved key names e.g. returnvalue that the matching POST endpoint already validated against FORBIDDENXCOMKEYS. The...