MacNewsBlog

Symantec warns of an unpatched Windows sharing security hole:

Hackers can attack Apple Inc.'s Mac OS X by exploiting an unpatched vulnerability in the open-source Samba file- and print-sharing software that's included with the operating system, Symantec Corp. said today. [...] "The DeepSight Threat Analyst Team successfully exploited the heap corruption vulnerability on a fully patched Mac OS X 10.4.9 system running the default Samba 3.0.10 application," said Symantec, in an alert to customers of its threat network. "Exploitation differs from what has been demonstrated in public exploits; however, it is likely that other researchers would be capable of quickly overcoming the technical quirks associated with the platform."
Although Mac OS X doesn't turn on Samba by default, Macs that share a network with Windows PCs could be at risk, Symantec warned. Because Apple has not released a Samba update since 2005, users must upgrade to the latest, and secure version, themselves.

Best thing to do is to disable and wait for Apple to patch it, or patch it yourself.