Xen was updated to fix several security issues:
CVE-2012-3433: A xen HVM guest destroy p2m teardown host DoS vulnerability was fixed, where malicious guest could lock/crash the host.
CVE-2012-3432: A xen HVM guest user mode MMIO emulation DoS was fixed.
CVE-2012-2625: The xen pv bootloader doesn't check the size of the bzip2 or lzma compressed kernel, leading to denial of service (crash).
Also the following bug in XEN was fixed:
This update also included bugfixes for: