Cross-site scripting (XSS) vulnerability in Outlook Web Access (OWA) in Microsoft Exchange Server 2013 PS1, 2013 Cumulative Update 10, and 2016 allows remote attackers to inject arbitrary web script or HTML via a crafted URL, aka "Exchange Spoofing Vulnerability."
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-010