The Jane Menu WordPress plugin before 1.5.1 does not have any capability or nonce checks on one of its form handlers, which is reachable by unauthenticated users, allowing them to bind any published page to a remote document of their choosing. The plugin then fetches that document and outputs its head and body into the page without escaping, so an unauthenticated attacker can run arbitrary JavaScript in the browser of any visitor to that page, including an administrator.