Source code of Counter Strike: Global Offensive and Team Fortress 2 has appeared online, developer and publisher Valve confirmed in two statements on Twitter. 

According to the company, this is probably code that was made available to third parties at the end of 2017. The source code could potentially be used to find vulnerabilities in the game. If successful and possible, a leak could be exploited by hackers and players to gain access to other players' computers. However, according to Valve, players of the current version of both games shouldn't have to worry. The company calls on players to use official servers "for the best possible security".

The code of both games is said to have leaked for the first time in 2018. It is unclear who is behind this time. Valve calls on people who have more information about the leaks to report it to the company.