Heads up! This vulnerability allows remote code execution. Nasty. Read the info, then get yourself updated.
Check it out: MS Security Update
Get the Mac Update here: Office Update
NOTE: Apparently, MicroSoft released a pre-release of another update. Users who were first in and updated are now reporting problems. MS suggests uninstalling the update. As of 12-13-06 morning, the download link is not functioning.
