Updated kernel packages that fix three security issues and several bugs arenow available for Red Hat Enterprise Linux 5.The Red Hat Security Response Team has rated this update as having moderatesecurity impact. Common Vulnerability Scoring System base scores,which give detailed severity ratings, are available for each vulnerabilityfrom the CVE links in the References section. The kernel packages contain the Linux kernel, the core of any Linuxoperating system.This update fixes the following security issues:* It was found that the Xen hypervisor implementation did not performrange checking on the guest provided values in multiple hypercalls. Aprivileged guest user could use this flaw to trigger long loops, leadingto a denial of service . * It was found that when running a 32-bit binary that uses a large numberof shared libraries, one of the libraries would always be loaded at apredictable address in memory. An attacker could use this flaw to bypassthe Address Space Layout Randomization security feature.* A flaw was found in the way the Linux kernel's IPv6 implementationhandled overlapping, fragmented IPv6 packets. A remote attacker couldpotentially use this flaw to bypass protection mechanisms when sending network packetsto 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 SecureDisclosure program and Loganaden Velvindron of AFRINIC for reportingCVE-2012-4444.This update also fixes several bugs. Space precludes documenting all ofthese changes in this advisory. Documentation for these changes will beavailable shortly from the Red Hat Enterprise Linux 5.9 Technical Notesdocument linked to in the References section.Users should upgrade to these updated packages, which contain backportedpatches to correct these issues. The system must be rebooted for thisupdate to take effect.