Plex Media Server before 1.43.3.10861 builds a file path from the url parameter without checking it for ../ sequences, allowing path traversal via '/system/agents/media/get'. A remote attacker with a valid session token could read any file that the target user can access. This access includes the PlexOnlineToken, which grants control of the Plex account and server. A LAN-adjacent attacker with a client-supplied X-Forwarded-For header could exploit the same issue.