Microsoft has released a security update for Exchange 2016 CU 10 and CU 11. The update fixes a manipulation vulnerability that has been classified as "Important":
A tampering vulnerability exists when Microsoft Exchange Server fails to properly handle profile data. An attacker who successfully exploited this vulnerability could modify a targeted user’s profile data.
To exploit the vulnerability, an attacker would need to be authenticated on an affected Exchange Server. The attacker would then need to send a specially modified request to the server, targeting a specific user.
The security update addresses the vulnerability by modifying how Microsoft Exchange Server handles profile data.
Source: CVE-2018-8604 | Microsoft Exchange Server Tampering Vulnerability
The update can be downloaded here: