The critical patch fixes a remote code execution vulnerability that could let hackers gain access to computers. The critical security update affects Windows 2000 Service Pack 4, Windows Vista, Windows XP SP2, Windows XP Professional x64 Edition and Windows XP Professional x64 Edition SP2.
Another security update, rated important, addresses a vulnerability that hackers could use to elevate a user's privilege level.
Microsoft will also release five, non-security, high-priority updates on Microsoft Update and Windows Server Update Services (WSUS), as well as two non-security, high-priority updates on Windows Update and WSUS. More information on the non-security updates will be available on Tuesday.
To find out if computer systems need all or any of these updates, IT administrators can use Microsoft's Baseline Security Analyzer.
An updated version of the Microsoft Windows Malicious Software Removal Tool will be released on January 8, on Windows Update, Microsoft Update, WSUS and Microsoft's download center.