Integer overflows were discovered in the functions grub_cmd_initrd and
grub_initrd_init in the efilinux component of GRUB2, as shipped in Debian,
Red Hat, and Ubuntu (the functionality is not included in GRUB2 upstream),
leading to a heap-based buffer overflow. These could be triggered by an
extremely large number of arguments to the initrd command on 32-bit
architectures, or a crafted filesystem with very large files on any
architecture. An attacker could use this to execute arbitrary code and
bypass UEFI Secure Boot restrictions. This issue affects GRUB2 version 2.04
and prior versions.

Colin Watson and Chris Coulson discovered that an integer overflow
existed in GRUB2 when handling the initrd command, leading to a heap-based
buffer overflow. A local attacker could use this to execute arbitrary code
and bypass UEFI Secure Boot restrictions.

sbeattie	efilinux: Fix integer overflows in grub_cmd_initrd e961f8f8cdb25245900dc0884047e856346035b3 Title: grub2: integer overflows in efilinux grub_cmd_initrd and grub_initrd_init leads to heap based buffer overflow code is not upstream in grub2 but carried as part of patches by Ubuntu, Debian, Red Hat and possibly others.
amurray	grub2-signed is not supported in Ubuntu 12.04 ESM (precise/esm) and so marking the priority for grub2 in this release as low