We have received few reports that a player have gone through a locked door. Our programmers are looking into this right now and if there is some such exploit they will fix it as soon as possible. In the mean time, just to be on the safe side, we suggest that you leave no items floating around in your world. Put a block over them. That way even if someone gets into area he’s not supposed to, he cannot pick up your items as they are inside a block.