An unspecified vulnerability was found in Microsoft Silverlight. By exploiting this vulnerability malicious users can bypass security restrictions. This vulnerability can be exploited remotely via an unknown vectors.
Microsoft Silverlight 5 versions earier than 5.1.30214.0
Silverlight 5 Developer Runtime versions earlier than 5.1.30214.0
Install necessary updates from the KB section, that are listed in your Windows Update (Windows Update usually can be accessed from the Control Panel)