Xen 3.0.3, 3.3.0, 3.3.1 - Unauthenticated Boot Parameter Modification via pyGrub
The pyGrub boot loader in Xen 3.0.3, 3.3.0, and Xen-3.3.1 does not support the password option in grub.conf for para-virtualized guests, which allows attackers with access to the para-virtualized guest console to boot the guest or modify the guest's kernel boot parameters without providing the expected password.