Grub in Debian AMD64

When booting from a 64bit Linux live CD and chrooting into my Debian AMD64 I get a segfault in Grub. I run the grub shell and enter:

root (hd0,4)
setup (hd0)

To prevent the setup command from segfaulting Grub, the live Linux needs to be booted with the following kernel parameter:

noexec=off

This seems to be a bug in Grub.