An update has been released for Left 4 Dead 2:

- Fixed a memory leak exploit in lobby chat.
- Prevent running arbitrary script code on a remote server.
- Prevent a network exploit that gave the client access to server settings.
- Implementation example for a new beta feature in Steam.

An update has been released for Left 4 Dead game and authoring tools:

- Fixes for several crash and remote code execution exploits.

An update has been released for Left 4 Dead 2:

- Fixed an exploit that could block a player from connecting to any game, whether online or local.
- Fixed two exploits that used invalid content to crash the game or prevent it from loading.
- Fixed a memory leak when rejecting invalid content.

An update has been released for Left 4 Dead 2:

- Fixed a bug that prevented the community server list from appearing.

An update has been released for Left 4 Dead 2:

- Fixed two exploits that could remotely crash servers.
- Fixed music not playing at the main menu on Linux.

An update has been released for Left 4 Dead:

- Fixed an exploit that could force votes to pass without notifying other players.
- Added protections against malicious network packets.
- Integrated several exploit fixes from Left 4 Dead 2.

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.

An update has been released for Left 4 Dead 2:

- Fixed two exploits that could crash remote servers.
- Fixed missing lobby state messages.
- Fixed community server searches not always returning the full set of lowest-ping results.

An update has been released for Left 4 Dead 2:

- Improved the reliability of "mm_dedicated_force_official_servers" to find the lowest ping server across the supplied IPs.