The Counter-Strike community has faced numerous challenges in the years since launch, ranging from cheating to gambling, but there's one more to add to the pile: a flood of chat bots. At least one intruder is taking advantage of a Counter-Strike: Global Offensive exploit to flood lobbies (even private ones) with text from chat bots that can't be kicked. From early indications, the attacker is trying to draw attention to security issues -- Valve supposedly doesn't care about cheaters and needs to be taught a lesson, if you believe the harasser.
The tricky part: there's no easy fix. Valve tells fans it has a "temporary solution" that should soften the blow, but it'll keep working on a fix "throughout next week." Unless the perpetrator has a change of heart, it could be difficult (or at least, extremely annoying) to play CS:GO for at least the next several days.