xen security update

CentOS Errata and Security Advisory CESA-2007:0323

The Xen package contains the tools for managing the virtual machine monitor
in Red Hat Enterprise Linux virtualization.

The following security flaws are fixed in the updated Xen package:

Joris van Rantwijk found a flaw in the Pygrub utility which is used as a
boot loader for guest domains. A malicious local administrator of a guest
domain could create a carefully crafted grub.conf file which would trigger
the execution of arbitrary code outside of that domain. (CVE-2007-4993)

Tavis Ormandy discovered a heap overflow flaw during video-to-video copy
operations in the Cirrus VGA extension code used in Xen. A malicious local
administrator of a guest domain could potentially trigger this flaw and
execute arbitrary code outside of the domain. (CVE-2007-1320)

Tavis Ormandy discovered insufficient input validation leading to a heap
overflow in the Xen NE2000 network driver. If the driver is in use, a
malicious local administrator of a guest domain could potentially trigger
this flaw and execute arbitrary code outside of the domain. Xen does not
use this driver by default. (CVE-2007-1321)

Users of Xen should update to these erratum packages containing backported
patches which correct these issues.

Merged security bulletin from advisories:
https://lists.centos.org/pipermail/centos-announce/2007-October/076428.html
https://lists.centos.org/pipermail/centos-announce/2007-October/076429.html

Affected packages:
xen
xen-devel
xen-libs

Upstream details at:
https://access.redhat.com/errata/RHSA-2007:0323