Microsoft has released its monthly set of security patches, fixing a critical flaw in Office. Attackers could exploit the bug by tricking Office users into opening a maliciously encoded .pub document, which would then allow attackers to run unauthorized software on a victim's PC. These .pub documents are created by Microsoft's Publisher software, an Office component used for designing print and online business publications.

For more information: http://www.microsoft.com/technet/security/bulletin/ms06-sep.mspx