Recently an exploit is witnessed wherein users who join your lobby could possibly enable several console commands leading to visibility through the walls, i.e. wallhacks. Eventually, Valve has taken down CS:GO lobbies while they investigate and solve the exploit. They further advised players to stay calm. Here is a list of console commands which can be accessed by the exploiters to malfunction the game:
This exploit was initially pointed out by users on r/GlobalOffensive. Several exploiters are targeting well known streamers to accuse them of using cheats and further get them banned. Jason ‘jasonR’ Ruchelski, Sébastien ‘krL’ Pérez, Joseph ‘mang0’ Marquez are various other streamers were plagued by the exploit.
The exploit is expected to be resolved sooner and till then, the lobby remains to stay down.
Note: An update was shipped by Valve earlier this morning to fix the exploit.