Important
Free support for Windows 10 Enterprise LTSC 2021 will end soon. For information about the availability of an Extended Security Update (ESU), see the End of support section.
Summary
This article lists the security issues and quality improvements included in this cumulative security update.
Applies to: Windows 10 ESU
Important
Use EKB KB5015684 to update to Windows 10, version 22H2.
This security update includes fixes and quality improvements that are part of the following updates:
The following is a summary of the issues that this update addresses when you install this update. If there are new features, it lists them as well. The bold text within the brackets indicates the item or area of the change we are documenting.
[Secure Boot] This update includes additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Certificate deployment via Windows updates continues across supported PCs and non-managed business devices in the coming months.
[Date and Time] This update adjusts Morocco Standard Time to reflect Morocco's transition to permanent UTC+00:00 effective September 20, 2026. This change ensures that the correct local time is displayed after the transition.
[OMA DM protocol] This update improves the logging features of the OMA DM Client (omadmclient.exe) component. More debug information is now saved when connecting to a server.
[Windows Code Integrity policies] Improves application compatibility during Windows certificate-authority rotation by recognizing Microsoft Windows Production PCA 2026 RSA2048-SHA256 as equivalent to PCA 2011.
[Remote Desktop] This update addresses an issue that affects Remote Desktop audio redirection. Audio from the remote session might not play on the local computer in certain configurations.
[BitLocker Group Policy] This update addresses the "Devices with an unrecommended BitLocker Group Policy configuration might be required to enter their BitLocker recovery key" known issue.
If you installed earlier updates, only the new updates contained in this package will be downloaded and installed on your device.
For more information about security vulnerabilities, please refer to the new Security Update Guide website and the September 2026 Security Updates.
For information about Windows update terminology, see the article about the types of Windows updates and the monthly quality update types. For an overview of Windows 10, version 22H2, see its update history page.
Known issues in this update
We are currently not aware of any issues with this update
Windows 10 servicing stack update (KB5122877) - version 19041.7714
Microsoft now combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). SSUs improves the reliability of the update process and includes fixes to the servicing stack, the component that installs Windows updates.
Note: This servicing stack update (SSU) includes enhanced logic to verify whether a device is hosted on Azure, leveraging an updated certificate chain for validation. To ensure that the device can access the required certificate update domains to successfully download and install certificate updates, see Certificate downloads and revocation lists and Azure Certificate Authority details. To learn more about SSUs, see Servicing stack updates.
How to get this update
Before you install this update
Important You must have the latest servicing stack update (SSU) installed. Not installing the latest SSU before applying Windows updates might result in the Windows update not being offered until the latest SSU is installed.
Deployment
If you deploy this update, choose one of the following based on your installation scenario:
- For offline OS image servicing: If your image does not have the July 25, 2023 (KB5028244) or later LCU, you must install the special standalone October 13, 2023 SSU (KB5031539) before installing this update.
- For Windows Server Update Services (WSUS) deployment or when installing the standalone package from Microsoft Update Catalog: If your devices do not have the May 11, 2021 (KB5003173) or later LCU, you mustinstall the special standalone August 10, 2021, SSU (KB5005260) before installing this update.
If you deploy dynamic updates such as this update to an existing Windows image, ensure the boot.stl file is included as part of the installation media. Failure to include the file might prevent devices from successfully starting from the installation media and can result in error code 0xc0430001.
Note
The boot.stl file is used during Secure Boot validation and must match the Windows version and architecture of the image you are updating.
To ensure the boot.stl file is included as part of the installation media, do one of the following:
- Use the Update WinPE script to update an existing Windows image. (Recommended)
- Manually copy the boot.stl file from the devices Windows\Boot\EFI folder to the corresponding folder on your installation media before deploying the update.
For information about how to apply Dynamic Update packages to existing Windows images, see Update Windows installation media with Dynamic Update.
Get and install this update
To get and install this update, use one of the following Windows and Microsoft release channels.
| Available | Next Step |
|---|---|
|
This update will be downloaded and installed automatically from Windows Update. |
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 KB5122878.
Download the file information for update SSU (KB5122877) - version 19041.7714.
Related topics
Microsoft Store application updates
Windows updates do not install Microsoft Store application updates. If you are an enterprise user, see Microsoft Store apps - Configuration Manager. If you are a consumer user, see Get updates for apps and games in Microsoft Store.Windows Secure Boot certificate expiration
Important: Secure Boot certificates used by most Windows devices have started expiring in June 2026. This might affect the ability of certain personal and business devices to boot securely if not updated in time. To avoid disruption, we recommend reviewing the guidance and taking action to update certificates in advance. For details and preparation steps, see Windows Secure Boot certificate expiration and CA updates.
- End of support
Microsoft will no longer provide free software updates from Windows Update, technical assistance, or security fixes on the following end dates. To continue to receive critical and important security updates for Windows 10, see Windows 10 Extended Security Updates (ESU). Otherwise, we recommend you upgrade to a later version of Windows.- Windows 10, version 21H2: Support ended on June 13, 2023
- Windows 10, version 22H2: Support ended on October 14, 2025
- Extended Security Updates (ESU) program for Windows 10
- Windows 10 Enterprise LTSC 2021: January 12, 2027. For information about the Extended Security Updates (ESU) program, see Plan for Windows 10 Enterprise LTSC 2021 end of support
- Windows 10 IoT Enterprise LTSC 2021: January 13, 2032
Change log
| Change date | Description |
|---|---|
| September 8, 2026 |
|