A security feature bypass vulnerability exists in the way that Office Click-to-Run (C2R) components handle a specially crafted file, which could lead to a standard user, any AppContainer sandbox, and Office LPAC Protected View to escalate privileges to SYSTEM.To exploit this bug, an attacker would have to run a specially crafted file, aka 'Microsoft Office ClickToRun Security Feature Bypass Vulnerability'.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1449