The original source codes of both Counter-Strike: Global Offensive (CS:GO) and Team Fortress 2 (TF2) were leaked online a few days back. While that would not matter much for the average player; for cheat-creators and exploiters though, it potentially opens up ways to bypass security measures and wreak havoc.
Taking to Twitter earlier today, Valve confirmed that the leaked source code of CS:GO was originally posted back in 2018 and is for an older version of the game. Taking into account how many security updates CS:GO has received since then, not to mention updates to the engine itself, Valve believes that players should have no reason to be alarmed. As such, the current build of CS:GO remains foolproof as long as players are joining the official servers.
That being said, Valve will continue to investigate the situation and provide updates when necessary. Should anyone know anything about the leak, they are requested to get in touch with Valve immediately.
We have reviewed the leaked code and believe it to be a reposting of a limited CS:GO engine code depot released to partners in late 2017, and originally leaked in 2018. From this review, we have not found any reason for players to be alarmed or avoid the current builds.
— CS:GO (@CSGO) April 22, 2020
The same goes for TF2 as well. Taking to Twitter around the same time, Valve reiterated that the leaked source code relates to an older leak from 2018. Like CS:GO, TF2 has taken additional security measures in the past few years and players should have no reason to be concerned as long as they are joining the official servers.
Regarding today's reported leak of code, specifically as it pertains to TF2: This also appears to be related to code depots released to partners in late 2017, and originally leaked in 2018.
— Team Fortress 2 (@TeamFortress) April 23, 2020
However, not everything has gone that smooth. According to Tyler McVicker, founder of Valve News Network, the leaked source codes have already led to an increased presence of cheats in both CS:GO and TF2. At least one TF2 community server has already closed down in response. There have also been claims that cheaters are gaining remote access to players in TF2 and sending them files without them even knowing about it. CS:GO, at least on the surface, looks to have fared the best of the two.