A remote code execution vulnerability exists in the way that ActiveX Data Objects (ADO) handle objects in memory. An attacker who successfully exploited the vulnerability could execute arbitrary code with the victim user’s privileges. An attacker could craft a website that exploits the vulnerability and then convince a victim user to visit the website. The security update addresses the vulnerability by modifying how ActiveX Data Objects handle objects in memory.
https://www.tenable.com/blog/tenable-roundup-for-microsofts-june-2019-patch-tuesday
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0888
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2019-0888