This security update resolves a Microsoft Excel remote code execution vulnerability. To learn more, see Microsoft Common Vulnerabilities and Exposures CVE-2021-31939.
Note: To apply this security update, you must have the release version of Microsoft Office Online Server installed on the computer.
Improvements and fixes
This update adds the xmlns attribute to the dependent assemblies in the Web.config file. This change enables Excel Online Web Parts that are created in an earlier version of SharePoint to work in Microsoft SharePoint 2019.
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.
Security update deployment information
For deployment information about this update, see Security update deployment information: June 8, 2021 (KB5004128).
Security update replacement information
This security update replaces previously released security update 5001914.
File hash information
Information about protection and security
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Learn how we guard against cyber threats: Microsoft Security