August 11, 2026—KB5120418 (OS Build 14393.9418)

Applies To
Windows Server 2016, all editions Win 10 Ent LTSB 2016 Win 10 IoT Ent LTSB 2016

Windows Secure Boot certificate expiration

Important Secure Boot certificates used by most Windows devices started to expire in June 2026. Microsoft has been updating these certificates on PCs and non-managed business devices for the past months. Devices that haven’t received the newer certificates will continue to start, and standard Windows updates will continue to install. We will continue to install the newer certificates via Windows updates in the coming months.

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.

  • [Backup] File History automatic backups to network shares using Server Message Block (SMB) might fail with an incorrect "invalid credentials" error. When this issue occurs, scheduled backups do not copy any files. This update resolves the issue.
  • [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.

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, see the Security Update Guide website and the August 2026 Security Updates.

For more information about Windows Server 2016, see its update history page.

For information about Windows update terminology, see types of Windows updates and monthly quality update types.

Known issues in this update

Microsoft is not currently aware of any issues with this update.

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 (KB5120236) 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 (KB5120236) 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 (KB5120236). 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 KB5120236 and this update KB5120418. 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
Available 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 Download the file information for cumulative update KB5120418.