Here are some of the most significant bugs from the past week in the BugBlog:
A security patch for Microsoft Office for the Mac was accidently released ahead of time via auto-update. According to the Microsoft Security Response Center blog, they are still testing this patch, and a pre-release version was accidently released. They've taken the patch out of circulation, and they also recommend that you uninstall the patch. See the Microsoft Security Response Center blog for the details.
There are two critical bugs in Windows Media Format files that can affect almost all current versions of Microsoft Windows. One bug is in the way that Windows handles Advanced Systems Format (ASF) files, and the other is in Advanced Stream Redirector (ASX) files. Run into one of the maliciously-designed files at a website or in email, and the attacker may be able to take control of your system. It affects Windows 2000, Windows XP, and Windows Server 2003, but not Windows Vista. It affects all versions of Microsoft Windows Media Format 7.1 through 9.5 Series Runtime, but version 11 is not affected. Microsoft has patches available.
Yahoo (I'm not putting in the exclamation point) says there is a bug in their Yahoo Messenger due to a bad ActiveX control. The bug may trigger a buffer overflow, which could be activated by visiting a maliciously designed web page. Yahoo says you may be vulnerable if you installed Yahoo Messenger before 11/2/06 (although they didn't post this notice until 12/8/06). You can get an update that fixes this bug.