An elevation of privilege vulnerability exists in Windows Setup in the way it handles permissions. A locally authenticated attacker could run arbitrary code with elevated system privileges. After successfully exploiting the vulnerability, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. The security update addresses the vulnerability by ensuring Windows Setup properly handles permissions.
https://www.tenable.com/blog/microsoft-s-august-2020-patch-tuesday-addresses-120-cves-cve-2020-1337
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1571