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 RHSA-2012:0862 update did not correctly fix the CVE-2011-4131 issue. A malicious Network File System version 4 server could return a crafted reply to a GETACL request, causing a denial of service on the client. * A divide-by-zero flaw was found in the TCP Illinois congestion control algorithm implementation in the Linux kernel. If the TCP Illinois congestion control algorithm were in use , a local, unprivileged user could trigger this flaw and cause a denial of service. * A NULL pointer dereference flaw was found in the way a new node"s hot added memory was propagated to other nodes" zonelists. By utilizing this newly added memory from one of the remaining nodes, a local, unprivileged user could use this flaw to cause a denial of service. * It was found that the initial release of Red Hat Enterprise Linux 6 did not correctly fix the CVE-2009-4307 issue, a divide-by-zero flaw in the ext4 file system code. A local, unprivileged user with the ability to mount an ext4 file system could use this flaw to cause a denial of service. * 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 Antonios Atlasis working with Beyond Security"s SecuriTeam Secure Disclosure program and Loganaden Velvindron of AFRINIC for reporting CVE-2012-4444. The CVE-2012-2375 issue was discovered by Jian Li of Red Hat, and CVE-2012-4565 was discovered by Rodrigo Freire of Red Hat. This update also fixes numerous bugs and adds one enhancement. Space precludes documenting all of these changes in this advisory. Documentation for these changes will be available shortly from the Red Hat Enterprise Linux 6.3 Technical Notes document linked to in the References section. Users should upgrade to these updated packages, which contain backported patches to correct these issues, fix these bugs and add the enhancement noted in the Technical Notes. The system must be rebooted for this update to take effect.