Microsoft plans to release up to 10 security updates to fix vulnerabilities in Windows, Internet Explorer, Word and Excel tomorrow.
If all 10 are released, this month's Patch Tuesday will be the largest single security update to Microsoft products since October last year.
According to Microsoft's advance notification, six updates will affect Windows and require a restart. Two of them are rated "critical" and relate to remote code execution.
One, rated "moderate", relates to information disclosure, and three rated as "important" relate to elevation of privilege vulnerabilities.
The other four planed updates are rated "critical" and will fix problems in Internet Explorer, Word, Excel and Microsoft Office.
The Internet Explorer update is critical on Windows Vista, XP and 2000, and will be the first IE8 update since its release in March.
The advance notification makes no mention of PowerPoint fixes for the Mac operating system.
Microsoft last month issued a patch for a critical PowerPoint vulnerability for all versions of Windows, but said Mac users would have to wait.
The advance notification also makes no mention of a DirectX or IIS vulnerabilities reported by Microsoft since the last security update.
Business IT administrators will have to wait until the June security update is released to see if these vulnerabilities will be covered.