A remote code execution vulnerability exists when the Windows Font Driver Host improperly handles memory. An attacker who successfully exploited the vulnerability would gain execution on a victim system. The security update addresses the vulnerability by correcting how the Windows Font Driver Host handles memory.
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-2020-1520