Exploit allows children to join online servers without permission

My son is able to join online servers despite being logged into his Xbox Live account, which is set to not allow this.

Immediately after launching the app, tap Play and then the Servers tab. Select a server. A message will appear saying you don't have permission to play online. Quickly, tap Play again and go to the Friends tab. The server will sometimes appear there as a LAN game, and it is fully joinable and playable.