KLA11289
Information disclosure vulnerability in Microsoft Downloads

An unspecified vulnerability was found in Mail, Calendar, and People in Windows 8.1 App Store. By exploiting this vulnerability malicious users can obtain sensitive information. This vulnerability can be exploited remotely via a specially designed e-mail message.

Mail, Calendar, and People in Windows 8.1 App Store

Install necessary updates from the KB section, that are listed in your Windows Update (Windows Update usually can be accessed from the Control Panel)