Post Syndicated from corbet original https://lwn.net/Articles/1082940/

The CMU CERT Coordination Center has put out an advisory that many
exploitable versions of the shim binary, used to boot Linux on systems with
UEFI secure boot enabled, were never added to the revocation list.

An attacker with administrative privileges or the ability to modify
the boot process could use one of the vulnerable shim bootloaders
to bypass Secure Boot protections and execute arbitrary code before
the operating system loads. Code executed during this early boot
phase may achieve persistent compromise of the platform, including
the ability to load unsigned or malicious kernel components that
can survive system reboots and, in some cases, operating system
reinstallation.

The advisory contains a list of vulnerable shims.