Description of the security update for Office Online Server: July 14, 2020

Applies to: Office Online Server


This security update resolves vulnerabilities in Microsoft Office that could allow remote code execution if a user opens a specially crafted Office file. To learn more about these vulnerabilities, see the following security advisories:

Note To apply this security update, you must have the release version of Office Online Server installed on the computer.

Improvements and fixes

This security update contains fixes for the following nonsecurity issues:
  • The Enter, up arrow, and down arrow keys navigate incorrectly in a workbook that has hidden columns. Pressing these keys moves an active cell to a hidden column instead of skipping hidden columns.
  • You open a workbook by using Excel Online, and pick a value from a list that’s defined by Data Validation. In some cases, if the text box is forced to grow (for example, by using a large font or text wrap), the edit box hides the first item in the list.

How to get and install the update

Method 1: Microsoft Update

This update is available from Microsoft Update. When you turn on automatic updating, this update will be downloaded and installed automatically. For more information about how to get security updates automatically, see Windows Update: FAQ.

Method 2: Microsoft Update Catalog

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Method 3: Microsoft Download Center

You can get the standalone update package through the Microsoft Download Center. Follow the installation instructions on the download page to install the update.

More information

Security update deployment information

For deployment information about this update, see security update deployment information: July 14, 2020.

Security update replacement information

This security update replaces previously released security update 4484290.

File hash information

File name SHA1 hash SHA256 hash
wacserver2019-kb4484451-fullfile-x64-glb.exe 1286FD6B0BECA66ED9DC47ECE6259BC100E7CBDA 258AA64B8FEE933311B9E717CD12027FA57E92E418AE79988A3D9AC68DCC7FA7

File information

Download the list of files that are included in security update 4484451.

Information about protection and security

Protect yourself online: Windows Security support

Learn how we guard against cyber threats: Microsoft Security