The Microsoft Office 2008 12.2.5 Update addresses 14 security vulnerabilities, the most serious of which pertain to maliciously crafted Excel files that could enable attackers to run arbitrary code and gain elevated system rights; accounts with administrative rights are at a greater risk than accounts with fewer privileges. The update addresses these issues by changing the way certain Excel files are parsed and by correcting certain installation problems with the Open XML File Format Converter for Mac. Additionally, the update fixes an issue with the custom dictionary that caused it to include words from other languages.
The update is rated Important for Microsoft Office 2008 for Mac and requires that you've previously installed the Microsoft Office 2008 for Mac 12.2.4 Update. The update is available from Microsoft's Web site and via the Office 2008 version of Microsoft AutoUpdate. (Free, 332.8 MB)