Microsoft’s latest monthly security update has caused issues for dual-boot Windows and Linux systems. The patch, aimed at fixing a two-year-old vulnerability in the GRUB open-source boot loader used by many Linux devices, is inadvertently stopping some Linux installs from booting properly.
Linux users are experiencing “security policy violation” messages and “something has gone seriously wrong” errors. The affected distributions include Ubuntu, Debian, Linux Mint, Zorin OS, and Puppy Linux.
Microsoft initially stated that the update would not affect dual-boot systems with both Windows and Linux installed. However, many users have reported issues despite this assurance. The patch was intended to fix a vulnerability allowing hackers to bypass Secure Boot, a technology used by Windows and Linux distributions to ensure malicious firmware is not loaded during boot.
There is currently no official statement from Microsoft regarding the issue, but a workaround has been discovered for Ubuntu users: disabling Secure Boot at the BIOS level and then logging into a Ubuntu user account to delete Microsoft’s SBAT policy.
Source: https://www.theverge.com/2024/8/21/24225108/microsoft-security-update-windows-linux-dual-boot-errors