The update does not provide any fixes and improvements, it’s solely a security update that resolves vulnerabilities in Microsoft Office that could allow remote code execution if a user opens a specially crafted Office file.

For more details see https://support.microsoft.com/en-us/help/4011026/description-of-the-security-update-for-office-online-server-june-12

You can download this update from https://www.microsoft.com/en-us/download/details.aspx?id=57042

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