The source code for both Team Fortress 2 and Counter-Strike: Global Offensive has been leaked online.
A tweet from the official Counter-Strike: Global Offensive twitter account says that the leaked code was a reposting of engine code from late 2017 that had subsequently leaked back in 2018.
Though Valve says it has "not found any reason for players to be alarmed or avoid the current builds," there have been concerns from various community-run servers that the code reveals a security vulnerability that could allow for remote code execution through either game, and Valve recommends only playing on official servers.
"All of this is more of a precaution than an actual threat," reads a Steam post from Red Sun. "Being able to actually see how the game's internals works means you can spot bugs that could allow for exploitation that otherwise could never have been found.
"Expect a rise in cheats, but wait back for word from Valve for anything else."