Ubuntu trims GRUB for secure boot in 26.10: strict /boot on ext4 and reduced feature set
Summary
Ubuntu 26.10 proposes stripping non-essential GRUB features to reduce the boot-time attack surface for secure boot. The proposal removes many filesystems, image formats, and partition table support, along with LVM and most RAID, requiring a lightweight ext4 /boot on GPT/MBR; encrypted setups must adapt accordingly. Upgrades to 26.10 will be disabled from 26.04 LTS, with secure-boot-enabled systems coexisting with non-secure boot options.