Rocket.Chat versions <8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, 7.13.9, 7.10.13 has an access control vulnerability in Livechat files. Protected file downloads at /file-upload/:fileId/:name authorize livechat access using rc_room_type=l with rc_rid+rc_token, but the authorization path does not verify that rc_rid matches the requested file's rid. Furthermore, :fileId is predictable via sequential MongoDB IDs, and :name can be anything, allowing unauthenticated discovery of all uploaded files.