This security update resolves a vulnerability in the VBScript scripting engine in Windows. The vulnerability could allow remote code execution if a user goes to a specially crafted website. An attacker who successfully exploited this vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs, could view, change, or delete data, or could create new accounts that have full user rights.
To learn more about the vulnerability, see Microsoft Security Bulletin MS15-066