Microsoft's holiday bonus: Fixes for 40 flaws

Microsoft today patched 40 vulnerabilities in Windows, Internet Explorer (IE), Office, SharePoint and Exchange, including nine pegged "critical."

Five of the 17 security updates -- Microsoft calls them "bulletins" -- fixed long-standing flaws that could be used by attackers to plant malware on a PC by tricking Windows into thinking a malicious DLL (dynamic link library) was actually a legitimate part of the OS.

Only two of the 17 updates were judged critical, Microsoft's top-most threat ranking in its four-step scoring system. Another 14 were marked "important," the second-highest rating, while the remaining update was labeled "moderate." Microsoft put the spotlight on the two critical bulletins, as did several security experts.