If exploited, the flaws could allow a remote attacker to crash an opponent s game client, take over the computer and hijack all computers connected to a third-party game server. The vulnerabilities were discovered in the network library of Steam, which is known as Steam Sockets. Steam is utilized by more than 25 million users, and serves as a platform for a number of wildly popular video games, including Counter Strike: Global Offensive, Dota2 and Half Life. Researchers disclosed the flaws to Valve in September; the vendor rolled out fixes after three weeks to different Steam games.
Source: https://threatpost.com/critical-steam-flaws-crash-opponents-computers/162100/