An elevation of privilege exists in the p2pimsvc service where an attacker who successfully exploited the vulnerability could run arbitrary code with elevated privileges. 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 update addresses this vulnerability by correcting how the p2pimsvc service handles processes these requests.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1168