A denial of service vulnerability exists when Connected User Experiences and Telemetry Service improperly handles file operations. An attacker who successfully exploited this vulnerability could cause a system to stop responding. To exploit the 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. The security update addresses the vulnerability by correcting how the Connected User Experiences and Telemetry Service handles file operations.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1123
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2020-1123