This month's Patch Tuesday will be a light one in comparison with those before it, with only three updates due next week. However, Microsoft's patch for Office shouldn't be taken lightly; its rating will be "Critical," the company said Thursday.

Past Patch Tuesdays have been significantly larger: August's contained 12 patches, and July brought seven fixes. Last September, however, Microsoft released no patches, although it scrapped a scheduled update that month due to a "quality issue."

The single critical patch planned for Office plays to the fact that hackers have made the productivity suite one of their favorite targets. Two dozen patches have already been issued for Office applications, with a significant number of them rated critical.

It is unclear what vulnerability the Office patch will fix, as Microsoft does not detail problems it intends to correct for users' security. But it's fairly likely that the fix wouldn't be for a recently publicized zero-day exploit for Word 2000, which some analysts say was overblown.

Besides the Office updates, Microsoft will also release two fixes for Windows, with the highest rating for either being "Important." Also on tap is the regular monthly update to Microsoft's Malicious Software Removal Tool, a staple of Patch Tuesday.

In addition to the security fixes, two non-security updates for Windows will appear through Windows Update, with three being released on Microsoft Update.