Applies ToWindows 10

Release Date:

8/13/2024

Version:

OS Build 10240.20751

12/8/20 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 1507, see its update history page.  

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.

Highlights

  • This update addresses security issues for your Windows operating system. 

Improvements 

This security update includes quality improvements. Below is a summary of the key issues that this update addresses when you install this KB. 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.

  • [BitLocker (known issue)] A BitLocker recovery screen shows when you start up your device. This occurs after you install the July 9, 2024, update. This issue is more likely to occur if device encryption is on. Go to Settings > Privacy & Security > Device encryption. To unlock your drive, Windows might ask you to enter the recovery key from your Microsoft account.

  • [Lock screen] This update addresses CVE-2024-38143. Because of this, the “Use my Windows user account” checkbox is not available on the lock screen to connect to Wi-Fi.

  • [NetJoinLegacyAccountReuse] This update removes this registry key. For more information refer to KB5020276—Netjoin: Domain join hardening changes.

  • [Secure Boot Advanced Targeting (SBAT) and Linux Extensible Firmware Interface (EFI)] This update applies SBAT to systems that run Windows. This stops vulnerable Linux EFI (Shim bootloaders) from running. This SBAT update will not apply to systems that dual-boot Windows and Linux. After the SBAT update is applied, older Linux ISO images might not boot. If this occurs, work with your Linux vendor to get an updated ISO image.

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 August 2024 Security Updates.

Known issues in this update

Symptom

Workaround

After installing this security update, you might face issues with booting Linux if you have enabled the dual-boot setup for Windows and Linux in your device. Resulting from this issue, your device might fail to boot Linux and show the error message “Verifying shim SBAT data failed: Security Policy Violation. Something has gone seriously wrong: SBAT self-check failed: Security Policy Violation.”

The August 2024 Windows security update applies a Secure Boot Advanced Targeting (SBAT) setting to devices that run Windows to block old, vulnerable boot managers. This SBAT update will not be applied to devices where dual booting is detected. On some devices, the dual-boot detection did not detect some customized methods of dual-booting and applied the SBAT value when it should not have been applied.

The September 2024 Windows security update (KB5043083​​​​​​​) and later updates do not contain the settings that caused this issue.

On Windows-only systems, after installing the September 2024 or later updates, you can set the registry key documented in CVE-2022-2601 and CVE-2023-40547 to ensure the SBAT security update is applied.

On systems that dual-boot Linux and Windows, there are no additional steps necessary after installing the September 2024 or later updates.

How to get this update

Before you install this update

Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU and applying Microsoft security updates.  For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions

If you are using Windows Update, the latest SSU (KB5041583) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog.

Install this update

To install this update, use one of the following Windows and Microsoft release channels.

Available

Next Step

Yes

None. This update will be downloaded and installed automatically from Windows Update and Microsoft Update.

Available

Next Step

Yes

None. This update will be downloaded and installed automatically from Windows Update for Business in accordance with configured policies.

Available

Next Step

Yes

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Available

Next Step

Yes

This update will automatically sync with Windows Server Update Services (WSUS) if you configure Products and Classifications as follows:

Product: Windows 10

Classification: Security Updates

File information

For a list of the files that are provided in this update, download the file information for cumulative update 5041782

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