Update: we have heard from Valve, who assures users that playing on official servers is perfectly safe. We’ve included their statement in the article below.

The source code for Team Fortress 2 has apparently been leaked, leading to hackers reportedly able to deliver malware through Remote Code Execution to other players.

This leak was initially reported by @SteamDB on Twitter, with the source code in question dating back to 2017 and 2018, affecting Counter-Strike: Source and Team Fortress 2. According to a report on the issue from PCGamesN, several Team Fortress 2 server communities have advised players to avoid the game until further notice.
…
Read full post here:
https://www.techradar.com/news/team-fortress-2-source-code-has-leaked-and-you-can-apparently-get-malware-by-playing