Critical AJAX Vulnerability - Security holes allow hacking of server

Well its possible to rout very large downloads through a system and use up its bandwidth, and its also possible to launch an attack at a system using an internal IP number if your going through the systems proxy.
Its an easy way to bypass a firewall if they have an internal proxy.

But this one seems to require some form of authentication so It dosnt seem to be open.
As for a dedicated host, if its a big business I would strongly recommend it.