Roger Pau Monne authored Dec 18, 2012 and Natanael Copa committed Dec 18, 2012

Excerpt from release notes:

This fixes the following critical vulnerabilities:
 * CVE-2012-4535 / XSA-20:
    Timer overflow DoS vulnerability
 * CVE-2012-4537 / XSA-22:
    Memory mapping failure DoS vulnerability
 * CVE-2012-4538 / XSA-23:
    Unhooking empty PAE entries DoS vulnerability
 * CVE-2012-4539 / XSA-24:
    Grant table hypercall infinite loop DoS vulnerability
 * CVE-2012-4544,CVE-2012-2625 / XSA-25:
    Xen domain builder Out-of-memory due to malicious kernel/ramdisk
 * CVE-2012-5510 / XSA-26:
    Grant table version switch list corruption vulnerability
 * CVE-2012-5511 / XSA-27:
    several HVM operations do not validate the range of their inputs
 * CVE-2012-5513 / XSA-29:
    XENMEM_exchange may overwrite hypervisor memory
 * CVE-2012-5514 / XSA-30:
    Broken error handling in guest_physmap_mark_populate_on_demand()
 * CVE-2012-5515 / XSA-31:
    Several memory hypercall operations allow invalid extent order
values
 * CVE-2012-5525 / XSA-32:
    several hypercalls do not validate input GFNs

We recommend all users of the 4.2.0 code base to update to this
point release.

Among many bug fixes and improvements (around 100 since Xen 4.2.0):
 * A fix for a long standing time management issue
 * Bug fixes for S3 (suspend to RAM) handling
 * Bug fixes for other low level system state handling
 * Bug fixes and improvements to the libxl tool stack
 * Bug fixes to nested virtualization