Windows 11, version 23H2 known issues and notifications
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Summary | Originating update | Status | Last updated |
---|---|---|---|
August 2024 security update might impact Linux boot in dual-boot setup devices This issue might impact devices with dual-boot setup for Windows and Linux when SBAT setting is applied | OS Build 22621.4037 KB5041585 2024-08-13 | Mitigated | 2024-09-20 12:41 PT |
Status | Originating update | History |
---|---|---|
Mitigated | OS Build 22621.4037 KB5041585 2024-08-13 | Last updated: 2024-09-20, 12:41 PT Opened: 2024-08-21, 18:33 PT |
After installing the August 2024 Windows security update, (KB5041585) or the August 2024 preview 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 and preview updates apply 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.
IMPORTANT: This known issue only occurs with the installation of the August 2024 security and preview updates. The September 2024 security update (KB5043076) and later updates do not contain the settings that caused this issue. If you install the September 2024 update, you don’t need to apply the workaround below.
Workaround:
If your Linux becomes unbootable after installing the August 2024 security or preview updates, you can recover your Linux system by following these instructions.
Important: This documentation contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, see How to back up and restore the registry in Windows. Also, note that modifying firmware settings incorrectly might prevent your device from starting correctly. Follow these instructions carefully and only proceed if you are confident in your ability to do so.
- Boot into your device’s firmware settings.
- Disable Secure Boot (steps vary by manufacturer).
- Boot into Linux.
- Open the terminal and run the below command:
sudo mokutil --set-sbat-policy delete
- Enter your root password if prompted.
- Boot into Linux once more.
- In the terminal, run the below command:
mokutil --list-sbat-revocations
- Ensure the list shows no revocations.
- Reboot into the firmware settings.
- Re-enable Secure Boot.
- Boot into Linux. Run the below command:
mokutil --sb-state
- The output should be “SecureBoot enabled”. If not, retry step d).
- Boot into Windows.
- Open Command Prompt as Administrator and run:
reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecureBoot\SBAT /v OptOut /d 1 /t REG_DWORD
At this point, you should now be able to boot into Linux or Windows as before. It’s a good time to install any pending Linux updates to ensure your system is secure.
NOTE: 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.
Next Steps: We are working on a final resolution that will be available in a future Windows update. We recommend you install the September 2024 update or later Windows updates to avoid this issue.
Affected platforms:
- Client: Windows 11, version 23H2; Windows 11, version 22H2; Windows 11, version 21H2; Windows 10, version 22H2; Windows 10, version 21H2; Windows 10 Enterprise 2015 LTSB
- Server: Windows Server 2022; Windows Server 2019; Windows Server 2016; Windows Server 2012 R2; Windows Server 2012
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