Debian Linux Security Advisory 2636-2 - A regression in combination with pygrub has been discovered. For the stable distribution (squeeze), these problems have been fixed in version 4.0.1-5.8.
ee72009eb00a50329387ebd0bcc9e9077fd8fb38c3b6a530a660483f4d1cb5f9
Debian Linux Security Advisory 2636-1 - Multiple vulnerabilities have been discovered in the Xen hypervisor.
c96f4d53b3c0573c21aa6543099fec9ebade88332214c9645241ab142e550f0b
Red Hat Security Advisory 2013-0241-01 - The xen packages contain administration tools and the xend service for managing the kernel-xen kernel for virtualization on Red Hat Enterprise Linux. A flaw was found in the way libxc, the Xen control library, handled excessively large kernel and ramdisk images when starting new guests. A privileged guest user in a para-virtualized guest could create a crafted kernel or ramdisk image that, when attempting to use it during guest start, could result in an out-of-memory condition in the privileged domain.
fd11e6102116bd2d5be286f2b61f3f09ef71df970c4fa155008b6fe5ad14aca5