This host is missing a critical security update according to Microsoft Bulletin MS13-022.
Successful exploitation could allow an attacker to execute arbitrary code. Impact Level: System/Application
Install the patch from below link, http://technet.microsoft.com/en-us/security/bulletin/ms13-022
The flaw is due to a double-free error when rendering a HTML object, which can be exploited via a specially crafted Silverlight application.
Microsoft Silverlight version 5 on Mac OS X