December 12, 2023—KB5033420 (Monthly Rollup)

IMPORTANT The installation of this Extended Security Update (ESU) might fail when you try to install it on an Azure Arc-enabled device that is running Windows Server 2012 R2. For a successful installation, please make sure all Subset of endpoints for ESU only are met as described in Connected Machine agent network requirements.

REMINDER

• Windows 8.1 reached end of support (EOS) on January 10, 2023, at which point technical assistance and software updates are no longer provided. If you have devices running Windows 8.1, we recommend upgrading them to a more current, in-service, and supported Windows release. If devices do not meet the technical requirements to run a more current release of Windows, we recommend that you replace the device with one that supports Windows 11.Microsoft will not be offering an Extended Security Update (ESU) program for Windows 8.1. Continuing to use Windows 8.1 after January 10, 2023 may increase an organization’s exposure to security risks or impact its ability to meet compliance obligations. For more information, see Windows 8.1 support will end on January 10, 2023.We recommend updating to a later version of Windows.Update to a later version of Windows
• Windows Server 2012 R2 reached end of support (EOS) on October 10, 2023. Extended Security Updates (ESUs) are available for purchase and will continue for three years, renewable on an annual basis, until the final date on October 13, 2026. For more information, see Windows Server End of Support: Key Dates. For information about the procedure to continue receiving security updates, see KB5031043.

We recommend upgrading to a later version of Windows Server.

Learn about upgrading Windows Server

• Windows Embedded 8.1 Industry Enterprise and Windows Embedded 8.1 Industry Pro reached end of support (EOS) on July 11, 2023. Therefore, technical assistance and software updates are no longer provided.

Summary

Learn more about this cumulative security update, including improvements, any known issues, and how to get the update.

NOTE For information about the various types of Windows updates, such as critical, security, driver, service packs, and so on, please see the following article. To view other notes and messages, see the Windows 8.1 and Windows Server 2012 R2 update history home page.

Improvements

This cumulative security update includes improvements that are part of update KB5032249 (released November 14, 2023). This update contains miscellaneous security improvements to internal Windows OS functionality. No specific issues are documented for this release.For more information about the resolved security vulnerabilities, please refer to the Deployments | Security Update Guide and the December 2023 Security Updates.

Known issues in this update

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

How to get this update

File information

For a list of the files that are provided in this update, download the file information for update KB5033420.

References

Learn about the standard terminology that is used to describe Microsoft software updates.