Critical flaw in Shim bootloader impacts major Linux distros

[rbc]

A critical vulnerability in the Shim Linux bootloader enables attackers to execute code and take control of a target system before the kernel is loaded, bypassing existing security mechanisms.

Shim is a small open-source bootloader maintained by Red Hat that is designed to facilitate the Secure Boot process on computers using Unified Extensible Firmware Interface (UEFI).

The tool is signed with a Microsoft key accepted by default on most UEFI motherboards that is used to verify the next stage of the boot process, typically loading the GRUB2 bootloader.
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Critical flaw in Shim bootloader impacts major Linux distros