An elevation of privilege vulnerability exists when Windows Lockscreen fails to properly handle Ease of Access dialog.An attacker who successfully exploited the vulnerability could execute commands with elevated permissions.The security update addresses the vulnerability by ensuring that the Ease of Access dialog is handled properly., aka 'Windows Lockscreen Elevation of Privilege Vulnerability'.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1398