You know, I really wonder why
some people hate Macs so much as to spread this disinformation.
The vulnerability about which he speaks is
a DHCP issue that has been around since NeXTSTEP. It has to do with the computer getting information from a malicious DHCP server and trusting that information. Now, while this is obviously a security issue that should be (and was) resolved, if you get hit by it, this hole is the least of your worries. You should be much more worried about how someone put a malicious DHCP server onto your network!