Two of the four bulletins will be rated "critical," Microsoft's highest severity rating. Those will cover remotely exploitable flaws in the Internet Explorer browser and the Microsoft Exchange Server.
[ GALLERY: How to configure Internet Explorer to run securely ]
The other two bulletins will carry an "important" severity rating and will provide fixes for code execution holes in Microsoft SQL Server and Microsoft Office (Visio).
The Internet Explorer update will apply to all supported versions of the Windows operating system, including Windows Vista and Windows Server 2008.