mod/chat/gui_sockets/index.php in Moodle through 2.1.10, 2.2.x before 2.2.11, 2.3.x before 2.3.8, 2.4.x before 2.4.5, and 2.5.x before 2.5.1 does not consider the mod/chat:chat capability before authorizing daemon-mode chat, which allows remote authenticated users to bypass intended access restrictions via an HTTP session to a chat server.