Microsoft SharePoint Enterprise Server 2013 SP1 and Microsoft SharePoint Enterprise Server 2016 allow an attacker to exploit a cross-site scripting (XSS) vulnerability by sending a specially crafted request to an affected SharePoint server, due to how SharePoint Server sanitizes web requests, aka "Microsoft Office SharePoint XSS Vulnerability". This CVE ID is unique from CVE-2017-11775 and CVE-2017-11777.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-11820