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Ubuntu Security Notice USN-3561-1
February 07, 2018

libvirt update
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 17.10
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Spectre mitigations were added to libvirt.

Software Description:
- libvirt: Libvirt virtualization toolkit

Details:

It was discovered that microprocessors utilizing speculative execution
and branch prediction may allow unauthorized memory reads via sidechannel
attacks. This flaw is known as Spectre. An attacker in the guest could use
this to expose sensitive guest information, including kernel memory.

This update allows libvirt to expose new CPU features added by microcode
updates to guests. On amd64 and i386, new CPU models that match the updated
microcode features were added with an -IBRS suffix. Certain environments
will require guests to be switched manually to the new CPU models after
microcode updates have been applied to the host.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 17.10:
  libvirt-bin                     3.6.0-1ubuntu6.2
  libvirt0                        3.6.0-1ubuntu6.2

Ubuntu 16.04 LTS:
  libvirt-bin                     1.3.1-1ubuntu10.17
  libvirt0                        1.3.1-1ubuntu10.17

Ubuntu 14.04 LTS:
  libvirt-bin                     1.2.2-0ubuntu13.1.25
  libvirt0                        1.2.2-0ubuntu13.1.25

After a standard system update you need to reboot your computer to make
all the necessary changes.

References:
  https://www.ubuntu.com/usn/usn-3561-1
  CVE-2017-5715

Package Information:
  https://launchpad.net/ubuntu/+source/libvirt/3.6.0-1ubuntu6.2
  https://launchpad.net/ubuntu/+source/libvirt/1.3.1-1ubuntu10.17
  https://launchpad.net/ubuntu/+source/libvirt/1.2.2-0ubuntu13.1.25