In August of last year, a security update intended to bolster the defenses of Secure Boot inadvertently disrupted the ability to dual-boot Windows and Linux on systems equipped with this feature. The update, which aimed to address a vulnerability in the GRUB bootloader, unfortunately allowed malicious actors to bypass Secure Boot’s protective measures. However, a timely resolution has emerged with Microsoft’s recent release of a patch on May 13, 2025, rectifying the situation nearly nine months after the initial issue was reported.
Windows is Dual-boot Friendly Again
Designated as KB5058385, this patch seeks to alleviate the complications introduced by the August 2024 update. It enhances the Secure Boot Advanced Targeting (SBAT) system’s ability to detect and interact with dual-boot configurations, particularly those that involve both Windows and Linux. The update refines the logic used to identify legitimate Linux bootloaders, effectively preventing them from being erroneously blocked or triggering “Security Policy Violation” alerts during the boot process.
This fix is applicable to several versions of Windows, including:
- Windows 11 23H2
- Windows 11 22H2
- Windows 11 21H2
- Windows 10 21H2
- Windows Enterprise 2015 LTSB
- Windows Server 2022
- Windows Server 2019
- Windows Server 2016
- Windows Server 2012
- Windows Server 2012 R2
As for obtaining this update, true to form, the patch will be automatically applied through Windows Update for affected installations. In my own experience with Windows 11 24H2, KB5058385 does not appear as a separate update, suggesting that the fix may already be integrated, although Microsoft has yet to confirm this.
Closing Thoughts
While it is certainly a relief that Microsoft has finally addressed this pressing issue, the timeline for resolution has been notably sluggish. Many dual-boot users found themselves grappling with malfunctioning setups, resorting to workarounds or even disabling Secure Boot entirely. This situation underscores a broader concern regarding the pace at which Microsoft responds to issues that do not directly impact their core Windows experience, particularly when it comes to niche but vital user communities like those who dual-boot with Linux.
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