A security update has been released which could allow remote code execution via a specially crafted Rich Text Format (RTF) e-mail message. The remote code would run with the same rights as the currently logged on used.
In addition, this security update offers fixes for 4 other security vulnerabilities.
View: Microsoft Security bulletin MS10-87
If you have Windows Update configured to also update other Microsoft applications, then this update will also also be offered via Windows Update or has already been updated automatically for you.