When a player has a lag he can temporary destroy blocks on the client side and then go through a wall and enter a secure house on the server side. WorldGuard in this situation teleports him back with a message 'you cant destroy here'.

Please do something quickly with this bug because it's a critical one

That is what the prevent-entry flag is for.

its completely different.

in sc on a lag you can destroy a wall on your client, go through it and then without a lag be inside a house on the server
in wg on a lag you can destroy a wall on your client, go through it and then without a lag your back outside the wall

fast breaking with nodus / efficiency pickaxe also works ;]

hmm, i'll check it out

Still waiting for a fix, this is a nasty bug.
It can easily be done by glitching though roofs.
And is very annoying.

Some footage of a douche bag I caught doing it live on camera:
https://www.youtube.com/watch?v=VPu6AFCKiHE