The MITRE CVE dictionary describes this issue as:
Multiple integer overflows in tools/libxc/xc_dom_bzimageloader.c in Xen 3.2, 3.3, 4.0, and 4.1 allow local users to cause a denial of service and possibly execute arbitrary code via a crafted paravirtualised guest kernel image that triggers (1) a buffer overflow during a decompression loop or (2) an out-of-bounds read in the loader involving unspecified length fields.
Find out more about CVE-2011-1583 from the
MITRE CVE dictionary dictionary and
This issue did not affect the versions of the Xen package as shipped with Red Hat Enterprise Linux 4 and 6. This has been addressed in Red Hat Enterprise Linux 5 via https://rhn.redhat.com/errata/RHSA-2011-0496.html.