Microsoft rated the upgrades as “important” in its security bulletin. Tuesday's release was part of a broader batch of updates that company observers said comprised Microsoft's second-largest "Patch Tuesday" in 2011.
The software updates improve security generally, the company said, but they also address vulnerabilities that could allow hackers to overwrite a Mac's memory with malicious code.
In a security bulletin, Microsoft said the vulnerability involved a “specially crafted Excel file” that, when opened by a Mac user, could give outside attackers the same administrative user rights as the computer's owner. The update adds a process for validating record information in specially crafted Excel files.
In addition to the Office updates, Microsoft also patched the Excel vulnerability in an upgrade to Open XML File Format Converter for Mac, a program that lets users convert Open XML files created in Office 2008 for Mac and edit them in earlier versions of the Office program.