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KB5126773: Cumulative security update for Internet Explorer: October 13, 2026

Applies To

Windows Server 2012 R2 ESU Windows Server 2012 ESU

Important

End of support information: Windows Server 2012 and Windows Server 2012 R2 reached the end of support on October 10, 2023. The Extended Security Updates (ESU) program for Windows Server 2012 and Windows Server 2012 R2 ended on October 13, 2026. This update is the final security update provided through the ESU program.

To continue receiving security and quality updates, we recommend that you upgrade to Microsoft Edge.

Important

Certain versions of Microsoft Internet Explorer have reached the end of support. Note that some versions of Internet Explorer may be supported past the latest OS end date when Extended Security Updates (ESUs) are available. See Lifecycle FAQ - Extended Security Updates for a list of products offering ESUs.

Summary

This security update resolves vulnerabilities in Internet Explorer. To learn more about these vulnerabilities, see Deployments | Security Update Guide.

Additionally, see the following articles for more information about cumulative updates:

This update applies to the following:

Internet Explorer 11 for Windows Server 2012 R2
Internet Explorer 11 for Windows Server 2012

Reminders

The improvements that are included in this Internet Explorer update are also included in the October 2026 Monthly Rollup. Installing either this Internet Explorer update or the Monthly Rollup installs the same improvements.

This update is not applicable for installation on a device on which the Monthly Rollup from October 2026 (or a later month) is already installed. This is because that update contains all the same improvements that are included in this Internet Explorer update.

If you use update management processes other than Windows Update and you automatically approve all security update classifications for deployment, this update and the October 2026 Monthly Rollup are deployed. We recommend that you review your update deployment rules to make sure that the desired updates are deployed.

If you install a language pack after you install this update, you must reinstall this update. Therefore, we recommend that you install any language packs that you need before you install this update. For more information, see Add language packs to Windows.

Known issues in this security update

We are currently not aware of any issues in this update.

How to get and install this update

Install this update

To install this update, use one of the following release channels.

Windows Update
Update for Business
Update Catalog
Server Update Services

Available	Next step
	This update is not available from Windows Update. See the Update Catalog, Update for Business, or the Server Update Services release channel.

Available	Next step
	This update will be downloaded and installed automatically from Windows Update in accordance with configured policies. For more information, see the following resources: What is Windows Update for Business? Configure Windows Update for Business

Available	Next step
	To get the standalone package for this update, go to the Microsoft Update Catalog website. To download updates from the Update Catalog, see Steps to download updates from the Windows Update Catalog.

Available	Next step
	This update will automatically sync with Windows Server Update Services (WSUS) if you have Products and Classifications configured as follows: Product: Specify your Windows operating system: Windows Server 2012 R2 Windows Server 2012 Classification: Security Updates

File information

A list of the files that are included in this update are provided in a CSV (Comma delimited) (*.csv) file. The file can be opened in a text editor such as Notepad or in Microsoft Excel.

Note: The English (United States) version of this software update might contain files for additional languages.

Download the file information for cumulative update KB5126773.

Information about protection and security

Protect yourself online: Windows Security support
Learn how we guard against cyber threats: Microsoft Security

References

Description of the standard terminology that is used to describe Microsoft software updates