Microsoft has released the KB5126657 Extended Security Update for Windows 10. It is available to Windows 10 Enterprise LTSC users and devices enrolled in the Extended Security Updates (ESU) program. The update does not introduce new system features, but it includes security and bug fixes, in addition to the changes announced as part of the October 2026 Patch Tuesday updates.
After the package is installed, Windows 10 is updated to version 19045.7807, while Windows 10 Enterprise LTSC 2021 reaches version 19044.7807. Eligible users can search for it manually by going to Settings, then Windows Update, and selecting Check for Updates.
What changes in the update?
KB5126657 includes fixes related to the October security update, which addressed 1,411 vulnerabilities in Microsoft products, including a zero-day vulnerability that the company said was being actively exploited. The update also includes a set of operational changes, most notably:
- Adding permanent daylight saving time support for the provinces of British Columbia and Alberta starting in November 2026.
- Adding the Manitoba Standard Time zone with the UTC-5:00 offset.
- Adding auditing capabilities and optional policy controls for ReFS volumes on externally attached storage devices. Auditing is enabled by default, while enforcement controls remain disabled by default.
- Fixing an issue that could leave some virtual disks in Storage Spaces Direct disconnected after a Windows update because of the incorrect interpretation of tiered storage data during recovery.
- Fixing a bug that could prevent File History from copying files to an external drive or network location, while displaying a message requesting that the backup drive be reconnected even though it was connected and working.
- Continuing the gradual deployment of updated Secure Boot certificates through Windows Update, based on targeting data used to identify devices eligible for automatic installation.
Audio issue not fully resolved
Microsoft warns of a known issue affecting some USB Audio Class 1.0 devices after Windows security updates released in September 2026. Affected devices may display a Code 10 message in Device Manager, audio may stop working, or volume and audio-setting controls may become unresponsive. Normal stereo audio may work, while eight-channel audio or 3D audio modes may fail.
Microsoft partially addressed this issue through an out-of-band emergency update released on September 14, but it fixed only issues with eight-channel and 3D audio modes. The company says that other audio issues remain and that it is working on additional fixes.
Why does this matter?
The update represents the security maintenance path available to organizations that still rely on Windows 10 editions covered by LTSC or ESU, rather than a feature upgrade for the system. Therefore, the practical priority is to install it on eligible devices, review ReFS controls before enabling enforcement, and test affected audio devices after the update. System administrators should also note that Secure Boot certificate deployment is continuing gradually, meaning that their arrival may vary between devices.