Tom Clancy's Rainbow Six: Siege players found they had unwelcome visitors entering their private lobbies recently, thanks to an exploit in the game that allowed an attacker to join any game lobby, even if it was set to private.
The good news is that a new hotfix has patched the exploit, meaning players no longer need to worry about intruders barging into their games. Before the patch dropped late last week though, anyone could jump into a squad and grief other gamers.
To fix an exploit where players could join lobbies uninvited, we have released a hotfix that will require PC players to have at least one friend already in the squad.— Rainbow Six Siege (@Rainbow6Game) January 8, 2021
Thank you for all your patience!
The fix is relatively simple, as the game now checks that the squad has at least one friend in it before you can join.
Some players were also finding their way into closed competitive matches recently too, all of which was made worse by the fact the game has no kick function. Still, the issue appears to be fixed, at least for now.... hopefully there aren't similar exploits just waiting to be found.