USN-3561-1: libvirt update

Ubuntu Security Notice USN-3561-1

7th February, 2018

libvirt update

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

  • Ubuntu 17.10
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS


Spectre mitigations were added to libvirt.

Software description

  • libvirt - Libvirt virtualization toolkit


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 version:

Ubuntu 17.10:
libvirt0 3.6.0-1ubuntu6.2
libvirt-bin 3.6.0-1ubuntu6.2
Ubuntu 16.04 LTS:
libvirt0 1.3.1-1ubuntu10.17
libvirt-bin 1.3.1-1ubuntu10.17
Ubuntu 14.04 LTS:
libvirt0 1.2.2-0ubuntu13.1.25
libvirt-bin 1.2.2-0ubuntu13.1.25

To update your system, please follow these instructions:

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