Important
Free support for Windows 10 Enterprise LTSB 2016 and Windows 10 IoT Enterprise 2016 LTSB ends on October 13, 2026. Free support for Windows Server 2016 ends soon. To learn about continuing support, see Plan for Windows Server 2016 and Windows 10 2016 LTSB end of support.
Summary
This article lists the security issues and quality improvements included in this cumulative security update.
Applies to: Windows Server 2016
This security update includes fixes and improvements that are a part of the following update:
The following is a summary of the issues that this update addresses. The bold text within the brackets indicates the item or area of the change we are documenting.
[Time and Date]
This update enables permanent Daylight Savings Time (DST) support for British Columbia and Alberta starting in November 2026.
This update introduces the new time zone Manitoba Standard Time "(UTC-5:00) Manitoba".
[ReFS security] This update adds auditing and optional policy controls for ReFS volumes on externally attached storage devices. Auditing is enabled by default, while enforcement controls remain disabled by default to give administrators time to evaluate and prepare for future security hardening changes. To learn more, see KB5130741.
[Distributed Key Manager (DKM)] This update automatically remediates insecure DKM container ACL configurations in AD FS by default. Administrators can opt out of automatic remediation by setting RemediateDkmAcl to 0. This change helps address an elevation of privilege vulnerability that can occur when the DKM container ACL is overly permissive. For more information about how to manage this change, see CVE-2026-56155: AD FS Distributed Key Manager container ACL hardening.
[Secure Boot] This update continues the deployment of updated Secure Boot certificates using the latest high-confidence targeting data to identify eligible devices that are ready to automatically receive the new certificates. Deployment through Windows Update remains ongoing across supported device.
Note If you installed earlier updates, only the new updates contained in this package will be downloaded and installed on your device.
For information about security vulnerabilities, see the Security Update Guide website and the October 2026 Security Updates.
Known issues in this update
USB Audio Class 1.0 devices with error Code 10 or no output
Symptoms
After installing the September 8, 2026, Windows security update, some USB Audio Class 1.0 devices might fail to start or produce audio. Affected devices might experience one or more of the following symptoms:
- The device displays an error in Device Manager: "This device cannot start (Code 10).”
- No audio output.
- Volume controls are unresponsive or remain at zero.
- Sound settings are unresponsive or unavailable.
- Some devices might function in standard stereo configurations but fail when using multichannel audio features, including 8-channel or 3D audio modes. Some customers have reported that they're able to restore audio in these cases by switching to 2-channel mode.
This issue is limited to USB Audio Class 1.0 devices.
Resolution
This issue is partially resolved in the out-of-band (OOB) update released on September 14, 2026. This OOB update resolves the symptoms experienced on devices using 8-channel or 3D audio modes. Microsoft is working to address the other symptoms and will provide more information when it is available.
IT administrators who need an immediate workaround for the symptoms not addressed yet by the OOB update should contact Microsoft Support for Business for assistance.
How to get this update
Before you install this update
To install updates released on or after January 14, 2025, we recommend that you first install the latest Servicing Stack Update (SSU). If your device or offline image does not have the latest SSU installed, you might not be able to install this update.
Caution
Until you install the SSU, this update might not be offered to your device. To reduce your security risk, install the SSU as soon as possible.
- If you use Windows Update, the latest SSU (KB5126649) will be offered to you automatically. If the latest SSU is not installed, you might not be able to install this update.
- If you use Windows Update for Business, the latest SSU (KB5126649) will be offered to you automatically. If the latest SSU is not installed, you might not be able to install this update.
- If you use the Update Catalog, we recommend that you download and install the latest SSU (KB5126649). If the latest SSU is not installed, you might not be able to install this update.
- If you are a Windows Server Update Services (WSUS) administrator, you must approve SSU KB5126649 and this update KB5126868. For general information about SSUs, see Servicing stack updates.
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 included in this update is provided in a CSV (Comma delimited) (*.csv) file. You can open the file 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 KB5126868.
References
For information about Windows 10, version 1607 or Windows Server 2016, see its update history page.
For information about Windows update terminology, see types of Windows updates and monthly quality update types.
Related topics
Microsoft Store application updates
Windows updates do not install Microsoft Store application updates. Enterprise users should see Microsoft Store apps - Configuration Manager. Consumer users should see Get updates for apps and games in Microsoft Store.Secure Boot certificate updates remain in progress as Microsoft transitions devices from certificates that began expiring in 2026 to newer certificates. Devices that have not yet received the newer certificates can continue to start and receive standard Windows updates. Microsoft will continue delivering the newer Secure Boot certificates to eligible devices through Windows Update.