An elevation of privilege vulnerability exists when the Storage Service improperly handles file operations. An attacker who successfully exploited this vulnerability could gain elevated privileges on the victim system. To exploit the vulnerability, an attacker would first have to gain execution on the victim system, then run a specially crafted application. The security update addresses the vulnerability by correcting how the Storage Services handles file operations.
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-2020-1490