It seems there are a significant number of hacks on Codeforces — and not the type where halyavin nukes your solution.
Just recently there were those 2 chinese guys who got accounts hacked (here).
Roughly a year before that there was this one round where a bunch of well-known reds had their submissions hacked and submitted by a horde of random accounts.
And now this post (here).
Are there any updates on these? How did they happen? Are the bugs fixed? I don't think I ever saw anything except "ok, we got hacked but 3 days later we got accounts back, problem solved".
I'm not trying to say nothing is being done, of course, there is probably a lot of good work going on behind the scenes, but it seems nobody knows what exactly is happening.