A flaw was found in the way Xen hypervisor checked for upper boundary when
getting a new event channel port. A privileged DomU user could use this
flaws to cause denial of service or, possibly, increase his privileges.
This issue does not affect upstream.
This issue only affects Red Hat Enterprise Linux 5 as we did not backport upstream Xen unstable commit 2dcdd2fcb945. The versions of the Linux kernel as shipped with Red Hat Enterprise Linux 4, 6, and Red Hat Enterprise MRG are not affected.
This issue has been addressed in following products:
Red Hat Enterprise Linux 5
Via RHSA-2011:0833 https://rhn.redhat.com/errata/RHSA-2011-0833.html