Microsoft has released security bulletin MS10-64 which applies to a security vulnerability in Outlook 2002/XP, 2003, 2007 and 2010. Previous version of Outlook are likely to be vulnerable as well, but no update will be released for these versions.
The security vulnerability exists when you have an Exchange account configured with the Cached Exchange Mode option turned off.
KB2315011: MS10-064: Vulnerability in Microsoft Office Outlook could allow remote code execution
The easiest way to get these updates and to install them is via Microsoft Update.
Note that if you are a home user and need support with these security updates, you’re entitled to no-charge support via your local Microsoft subsidiary.