Microsoft said, Patch Tuesday would include eight patches, five of them critical, including one addressing a vulnerability in Excel. A company representative declined to confirm whether the patch for its spreadsheet software addresses a vulnerability that has seen "zero-day attacks" which target unpatched security holes. But given the fact that both that Excel vulnerability and the Excel patch slated for Tuesday affect Microsoft Office 2000, 2002, 2003, and 2007, as well as Microsoft Office 2004 and 2008 for the Mac, it could be the same weakness.

More info: Microsoft Security Bulletin