Recently, popular CS:GO Twitter personality @DonHaci posted a video that shows a player using an exploit that by-passes Valve's anti-cheat software undetected. This can be easily activated using the in-game console without the hassle of using any external third-party softwares.
In the video the user can be seen entering a match and then simply opening the console to type ‘sv_cheats 1’, allowing him to see other players through walls and other in-game obstructions.
Haci went on to state that this is a longstanding exploit that has been in use for years now.
This exploit surfaces days after another bug was revealed that gave the CT-side on the B site of Dust 2 a slight advantage. With the issue now gaining significant attention, Counter-Strike devs will hopefully roll out a patch soon, to resolve this issue.
Until then players are advised to keep away from competitive matchmaking as there is likely going to be an increased number of cheaters abusing the exploit. No official communication has been put out by Valve yet.