Source: Steam Powered

Updates to the Source 2007 Engine have been released. The updates will be applied automatically when your Steam client is restarted. The specific changes include:

Source 2007 Engine

• Fixed an exploit that allowed files to be uploaded to the server at arbitrary locations in the file system


• Fixed a server crash caused by a client packet claiming to be an HLTV client when HLTV is disabled on the server


• Fixed a server crash caused by spoofing a client disconnect message


• Fixed a server crash caused by sending malformed reliable subchannel data

On a side note...I think this is the first time I can remember the Source Engine being refered to as the "Source 2007 Engine". Maybe I have not been paying attention but this could mean a possible major update to the engine itself is coming soon.