Grub2: missing unregister call for normal_exit command may lead to use-after-free

A vulnerability in the GRUB2 bootloader has been identified in the normal module. This flaw, a memory Use After Free issue, occurs because the normal_exit command is not properly unregistered when its related module is unloaded. An attacker can exploit this condition by invoking the command after the module has been removed, causing the system to improperly access a previously freed memory location. This leads to a system crash or possible impacts in data confidentiality and integrity.