A security feature bypass vulnerability exists when the Microsoft Outlook attachment block filter does not properly handle attachments. An attacker who successfully exploited the vulnerability could execute arbitrary commands. The security feature bypass by itself does not allow arbitrary code execution. In a file-sharing attack scenario, an attacker could provide a specially-crafted document file designed to exploit the vulnerability, and then convince a user to open the document file. The update addresses the vulnerability by correcting how the Microsoft Outlook attachment block filter handles attachments.