Just last week, we saw a new zero-day attack [1] that affected basically every version of Microsoft Word currently in use. In case that didn't worry you, this might: a second zero-day attack for Word has been identified and some security vendors have labeled the exploit "extremely critical," as the vulnerability remains unpatched, as with the first attack. Effected versions of Word are: Word 2000, Word 2002, Word 2003 and Word Viewer 2003.

For more details:
- see this ZDnet article [2]