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Ubuntu Security Notice USN-3576-1
February 20, 2018

libvirt vulnerabilities
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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:

Several security issues were fixed in libvirt.

Software Description:
- libvirt: Libvirt virtualization toolkit

Details:

Vivian Zhang and Christoph Anton Mitterer discovered that libvirt
incorrectly disabled password authentication when the VNC password was set
to an empty string. A remote attacker could possibly use this issue to
bypass authentication, contrary to expectations. This issue only affected
Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2016-5008)

Daniel P. Berrange discovered that libvirt incorrectly handled validating
SSL/TLS certificates. A remote attacker could possibly use this issue to
obtain sensitive information. This issue only affected Ubuntu 17.10.
(CVE-2017-1000256)

Daniel P. Berrange and Peter Krempa discovered that libvirt incorrectly
handled large QEMU replies. An attacker could possibly use this issue to
cause libvirt to crash, resulting in a denial of service. (CVE-2018-5748)

Pedro Sampaio discovered that libvirt incorrectly handled the libnss_dns.so
module. An attacker in a libvirt_lxc session could possibly use this issue
to execute arbitrary code. This issue only affected Ubuntu 16.04 LTS and
Ubuntu 17.10. (CVE-2018-6764)

Update instructions:

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

Ubuntu 17.10:
  libvirt-bin                     3.6.0-1ubuntu6.3
  libvirt0                        3.6.0-1ubuntu6.3

Ubuntu 16.04 LTS:
  libvirt-bin                     1.3.1-1ubuntu10.19
  libvirt0                        1.3.1-1ubuntu10.19

Ubuntu 14.04 LTS:
  libvirt-bin                     1.2.2-0ubuntu13.1.26
  libvirt0                        1.2.2-0ubuntu13.1.26

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

References:
  https://www.ubuntu.com/usn/usn-3576-1
  CVE-2016-5008, CVE-2017-1000256, CVE-2018-5748, CVE-2018-6764

Package Information:
  https://launchpad.net/ubuntu/+source/libvirt/3.6.0-1ubuntu6.3
  https://launchpad.net/ubuntu/+source/libvirt/1.3.1-1ubuntu10.19
  https://launchpad.net/ubuntu/+source/libvirt/1.2.2-0ubuntu13.1.26