A memory corruption vulnerability exists in the Windows DHCP client when an attacker sends specially crafted DHCP responses to a client. An attacker who successfully exploited the vulnerability could run arbitrary code on the client machine. To exploit the vulnerability, an attacker could send specially crafted DHCP responses to a client. The security update addresses the vulnerability by correcting how Windows DHCP clients handle certain DHCP responses.
https://www.tenable.com/blog/tenable-roundup-for-microsoft-s-august-2019-patch-tuesday-dejablue
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0736