A remote code execution vulnerability exists when the Microsoft XML Core Services MSXML parser processes user input, aka 'MS XML Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2019-0790, CVE-2019-0792, CVE-2019-0793, CVE-2019-0795.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0791