A Security Update has been released for Outlook 2013. It resolves the following vulnerability;
Which could allow remote code execution via a specially crafted file attachment which must be opened by a user.
Update: An additional update (KB4011029) has been released this month which solves an issue with mail delivery rules stopping to work and opening the Mange Rules & Alerts dialog returns the following error;
The operation failed because of a registry or installation problem. Restart Outlook and try again. If the problem persists, reinstall.
Note: This update can be installed via Microsoft Update or the Update Now button when you are using Office 2013 Click-To-Run and updates Outlook to version 15.0.5093.1000 and the updated release to version 15.0.5093.1001.