KLA10736
Spoofing vulnerability in Microsoft Exchange Server

Improper web requests handling was found in Microsoft Exchange Server at Outlook Web Access. By exploiting this vulnerability malicious users can spoof user interface. This vulnerability can be exploited remotely via a specially designed email with malicious link.

Microsoft Exchange Server 2016
Microsoft Exchange Server 2013 Service Pack 1
Microsoft Exchange Server 2013 Cumulative Update 10
Microsoft Exchange Server 2013 Cumulative Update 11

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