GRUB2 (short-form option parser): Heap out-of-bounds write in the short-form option parser

Impact

Heap out-of-bounds write in the short-form option parser. Another arbitrary-write primitive inside the signed bootloader, usable to load unsigned code with Secure Boot enabled.

Who can reach it

Local, via GRUB command line or grub.cfg.

What to do

grub2 package update + reboot per node, followed by the dbx pass if you are actually revoking old binaries.

References