The kernel packages contain the Linux kernel, the core of any Linux operating system. This update fixes the following security issues: * It was found that the Xen hypervisor implementation did not perform range checking on the guest provided values in multiple hypercalls. A privileged guest user could use this flaw to trigger long loops, leading to a denial of service . * It was found that when running a 32-bit binary that uses a large number of shared libraries, one of the libraries would always be loaded at a predictable address in memory. An attacker could use this flaw to bypass the Address Space Layout Randomization security feature. * A flaw was found in the way the Linux kernel"s IPv6 implementation handled overlapping, fragmented IPv6 packets. A remote attacker could potentially use this flaw to bypass protection mechanisms when sending network packets to a target system. Red Hat would like to thank the Xen project for reporting CVE-2012-5515, and Antonios Atlasis working with Beyond Security"s SecuriTeam Secure Disclosure program and Loganaden Velvindron of AFRINIC for reporting CVE-2012-4444. This update also fixes several bugs. Space precludes documenting all of these changes in this advisory. Documentation for these changes will be available shortly from the Red Hat Enterprise Linux 5.9 Technical Notes document linked to in the References section. Users should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.