xploraiswakco writes with the first Microsoft-confirmed Windows 7 zero-day
vulnerability, with a demonstration exploit publicly available. The problem is in SMBv2 and SMBv1 and affects Windows 7 and Windows Server 2008 R2, but not Vista, XP, or Windows Server 2003. A maliciously crafted URI could hard-crash affected machines beyond any remedy besides pushing the white button. "Microsoft said it may patch the problem, but didn't spell out a timetable or commit to an out-of-cycle update before the next regularly-scheduled Patch Tuesday of December 8. Instead, the company suggested users block TCP ports 139 and 445 at the firewall."
Reader xploraiswakco adds, "As important as this the mentioned article is, it should also be pointed out that any IT staff worth their pay packet should already have port 139 blocked at the firewall, and probably port 445, too."