August 2024 OS security update (KB 5041573) for Azure Stack HCI, version 23H2

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Applies to: Azure Stack HCI, version 23H2

This article describes the OS security update for Azure Stack HCI, version 23H2 that was released on August 13, 2024 and applies to OS build 25398.1085.

Improvements

This security update includes quality improvements. The following key issues and features are present in this update:

  • Stability of clusters on Windows Server 2022. Servers in the same cluster shutdown when you don't expect them to. This leads to high latency and network availability issues.

  • Bootloader. A race condition might stop a computer from starting. This occurs when you configure the bootloader to start many operating systems.

  • Autopilot. Using Autopilot to provision a Surface Laptop SE device fails.

  • Windows Defender Application Control (WDAC). A memory leak occurs that might exhaust system memory as time goes by. This issue occurs when you provision a device.

  • Protected Process Light (PPL) protections. You can bypass them.

  • Windows Kernel Vulnerable Driver Blocklist file (DriverSiPolicy.p7b). This update adds to the list of drivers that are at risk for Bring Your Own Vulnerable Driver (BYOVD) attacks.

  • NetJoinLegacyAccountReuse. This update removes this registry key. For more information, see KB 5020276 Net join: Domain join hardening changes.

  • 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. As a result, the Use my windows user account check box isn't available on the lock screen to connect to Wi-Fi.

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

  • Domain Name System (DNS). This update hardens DNS server security to address CVE-2024-37968. If the configurations of your domains aren't up to date, you might get the SERVFAIL error or a time-out.

For more information about security vulnerabilities, see the Security Update Guide and the August 2024 Security Updates.

Known issues

Microsoft isn't currently aware of any issues with this update.

To install this update

Microsoft now combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

To install the LCU on your Azure Stack HCI cluster, see Update Azure Stack HCI clusters.

File list

For a list of the files that are provided in this update, download the file information for Cumulative update 5041573.

Next steps