This security update resolves vulnerabilities in Microsoft Office. The most severe of the vulnerabilities could allow remote code execution if a user opens a specially crafted Microsoft Office file. An attacker who successfully exploited the vulnerabilities could run arbitrary code in the context of the current user. Customers whose accounts are configured to have fewer user rights on the system could be less affected than those who operate by having administrative user rights.
To learn more about these vulnerabilities, see Microsoft Security Bulletin MS15-131
For a complete list of affected versions of Office software, see Microsoft Knowledge Base article 3116111