An update has been released for Left 4 Dead 2:

- Fixed another exploit where malicious network packets could severely degrade server performance.
- Fixed a client exploit that could cause long server stalls.
- Fixed a potential crash if a Charger failed to return to valid nav for an extended period of time.
- Fixed a rare hang from ray traces encountering NaN values.

An update has been released for Left 4 Dead 2:

- Blocked an exploit that could forcibly disconnect a player from any server, even when playing a local game.