Microsoft CVE-2019-1137: Microsoft Exchange Server Spoofing Vulnerability

A cross-site-scripting (XSS) vulnerability exists when Microsoft Exchange Server does not properly sanitize a specially crafted web request to an affected Exchange server. An authenticated attacker could exploit the vulnerability by sending a specially crafted request to an affected server.
The attacker who successfully exploited the vulnerability could then perform cross-site scripting attacks on affected systems and run script in the security context of the current user. The attacks could allow the attacker to read content that the attacker is not authorized to read, use the victim's identity to take actions on the Exchange server on behalf of the user, such as change permissions and delete content, and inject malicious content in the browser of the user.
The security update addresses the vulnerability by helping to ensure that Exchange Server properly sanitizes web requests.