(RHSA-2016:0004) Important: kernel security update

The kernel packages contain the Linux kernel, the core of any Linux
operating system.

• It was found that the x86 ISA (Instruction Set Architecture) is prone to
  a denial of service attack inside a virtualized environment in the form of
  an infinite loop in the microcode due to the way (sequential) delivering of
  benign exceptions such as #AC (alignment check exception) and #DB (debug
  exception) is handled. A privileged user inside a guest could use these
  flaws to create denial of service conditions on the host kernel.
  (CVE-2015-5307, CVE-2015-8104, Important)

Red Hat would like to thank Ben Serebrin of Google Inc. for reporting the
CVE-2015-5307 issue.

All kernel users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. The system must be
rebooted for this update to take effect.