I've been reading about this for the last hour or so. Doesn't seem like there is any solid proof hackers can execute remote code, its all pictures and no video demonstrations.
Its also source code from 2018 with rumors that its been out there for just as long, and that its probably responsible for all the bots that plagued casual. On top of that it isn't even the entire source code, just a larger chunk of it. You can't compile it in to a working game.
On top of that, I really doubt Steam as a whole is so vulnerable that a game could give hackers full control over someones Steam profile. If it was that bad Valve would have said something by now I'm sure, as they puts everyone at risk.