Authorization Bypass Through User-Controlled Key (CWE-639) in Fleet Server can lead to information disclosure via Manipulating User-Controlled Variables (CAPEC-77). The authorization decision for artifact downloads relied on a client-supplied value that was persisted without being validated against the server-side record of the requesting agent's assignment. An authenticated party in possession of a valid enrolled agent credential could therefore retrieve a policy the agent is not assigned to.
https://discuss.elastic.co/t/fleet-server-8-19-20-9-4-5-9-5-1-security-update-esa-2026-112/389509