Microsoft Update Breaks Dual-Boot Systems, Leaving Linux Users Locked Out

Microsoft’s most recent security update has inadvertently caused major problems for users with dual-boot systems running both Windows and Linux, The Verge reports. Intended to fix a long-standing vulnerability in the GRUB boot loader—used by many Linux distributions—the update is now preventing some Linux installations from booting altogether.

The update, designed to address a two-year-old vulnerability that allowed attackers to bypass Secure Boot, a critical feature that prevents unauthorised firmware from loading during startup, was not supposed to affect dual-boot systems. Microsoft had assured users that the patch, part of its Secure Boot Advanced Targeting (SBAT) update, would not impact systems running both Windows and Linux. However, many users are now encountering serious issues.

Reports have emerged from various online fora, including Reddit and the Ubuntu community, where users have described encountering “security policy violation” errors and ominous messages like “something has gone seriously wrong” when trying to boot into their Linux operating systems. Distributions such as Ubuntu, Debian, Linux Mint, Zorin OS, and Puppy Linux are among those affected.

The disruption has left many users unable to access their Linux installations, leading to widespread frustration.

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Microsoft has not yet issued an official statement on the matter, but a workaround has been identified for Ubuntu users. This temporary fix involves disabling Secure Boot in the BIOS, which then allows users to boot into Ubuntu and remove the problematic SBAT policy via a terminal command.

Secure Boot has long been a cornerstone of Microsoft’s security strategy, especially with the introduction of Windows 11, where it is a mandatory feature to protect against BIOS rootkits. Despite its importance, Secure Boot has had its share of vulnerabilities over the years, with recent findings revealing that it remains compromised on many systems.

This situation underscores the complexities of maintaining seamless compatibility across different operating systems and the unintended consequences that can arise from broad security updates. As users grapple with these issues, many are eagerly awaiting a more permanent solution from Microsoft.