KB5041578: This update stops vulnerable Linux EFI (Shim bootloaders) from running

August 13, 2024—KB5041578 (OS Build 17763.6189)

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

Improvements
This security update includes 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.

- [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.

- [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” check box 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.

- [Domain Name System (DNS)] This update hardens DNS server security to address CVE-2024-37968. If the configurations of your domains are not up to date, you might get the SERVFAIL error or time out.

- [Line Printer Daemon (LPD) protocol] Using this deprecated protocol to print might not work as you expect or fail. This issue occurs after you install the July 9, 2024, and later updates.

Note When it is no longer available, clients, like UNIX, that use it will not connect to a server to print. UNIX clients should use the Internet Printing Protocol (IPP). Windows clients can connect to shared UNIX printers using the Windows Standard Port Monitor.

If you installed earlier updates, only the new updates contained in this package will be downloaded and installed on your device.