A security feature bypass vulnerability exists when Internet Explorer fails to validate User Mode Code Integrity (UMCI) policies. The vulnerability could allow an attacker to bypass Device Guard UMCI policies.
To exploit the vulnerability, a user could either visit a malicious website or an attacker with access to the system could run a specially crafted application. An attacker could then leverage the vulnerability to run unsigned malicious code as though it were signed by a trusted source.
The update addresses the vulnerability by correcting how Internet Explorer validates UMCI policies.