A security feature bypass vulnerability exists where a NETLOGON message is able to obtain the session key and sign messages.To exploit this vulnerability, an attacker could send a specially crafted authentication request, aka 'Microsoft Windows Security Feature Bypass Vulnerability'.
https://www.tenable.com/blog/tenable-roundup-for-microsofts-june-2019-patch-tuesday
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1019