The xen packages contain administration tools and the xend service for managing the kernel-xen kernel for virtualization on Red Hat Enterprise Linux.
It was found that the xc_try_bzip2_decode() and xc_try_lzma_decode() decode routines did not correctly check for a possible buffer size overflow in the decoding loop. As well, several integer overflow flaws and missing error/range checking were found that could lead to an infinite loop. A privileged guest user could use these flaws to crash the guest or, possibly, execute arbitrary code in the privileged management domain (Dom0). (CVE-2011-1583)
All xen users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.