Summary

This security update resolves a spoofing vulnerability that exists when Office Online does not validate origin in cross-origin communications handlers correctly. To learn more about the vulnerability, see the following security advisories:

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

Known issues in this update

  • After you install this security update, Office Online Server logging will be set to Verbose by default. We recommend that you change this setting to Medium by running the following command:

    Set-OfficeWebAppsFarm -LogVerbosity “Medium”

    Note After you run the command, you have to restart the Office Online Service. To do this, run the following command:

    Restart-Service WACSM

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: November 12, 2019.

Security update replacement information

This security update replaces previously released security update 4475595.

File hash information

File name

SHA1 hash

SHA256 hash

wacserver2019-kb4484141-fullfile-x64-glb.exe

40327E2F21EC02766F5AD208DC18837896DA953B

D9F19DC0B0DAA0CC981C8154E5769301A503C581349886B7C548082BAB0F304B

File information

Download the list of files that are included in security update 4484141.

How to get help and support for this security update

Help for installing updates: Protect yourself online Help for protecting your Windows-based computer from viruses and malware: Microsoft Security Local support according to your country: International Support

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