Windows 10 1607-1903 & Server 2016-2019 Privilege Escalation via AppX Deployment Service
An elevation of privilege vulnerability exists when Windows AppX Deployment Service (AppXSVC) improperly handles hard links. An attacker who successfully exploited this vulnerability could run processes in an elevated context. An attacker could then install programs; view, change or delete data.
To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and take control of an affected system.
The security update addresses the vulnerability by correcting how Windows AppX Deployment Service handles hard links.