Microsoft has released a new security update for Windows XP x64 Edition, Windows Server 2003 x64 Edition, and Windows Server 2003 for Itanium-based Systems

A security issue has been identified in the Server service that could allow an attacker to compromise your Windows-based system and gain control over it. You can help protect your computer by installing this update from Microsoft. After you install this item, you may have to restart your computer.

Security Update for Windows XP x64 Edition (KB921883)
Security Update for Windows Server 2003 x64 Edition (KB921883)
Security Update for Windows Server 2003 for Itanium-based Systems (KB921883)