The Internet Explorer security leak, for which a patch is now available, could also affect your Outlook security. This is only the case when you are working with Outlook 2003 and previous and have your Internet Security Zone for Outlook set to the Internet Zone. Outlook 2007 and Outlook 2010 Beta are not affected.
Currently there are no known exploits of this security leak that work via Outlook 2003 or previous. However, in order to protect yourself, make sure you have your Security Zone for Outlook 2003 or previous set to “Restricted sites”. This zone is also the secure default and the recommended setting. You can verify this setting by going to;
Tools-> Options…-> tab Security
This exploit could also surface via other parts of Windows (such as via Gadgets, Outlook Express, Windows (Live) Mail and the Help system (chm-files)) since they all rely on Internet Explorer components. So even when you are not using Internet Explorer as your Internet browser, it is still highly recommended to install this update as soon as possible.
You can get this update via Windows Update as well.