Several security issues were fixed in libvirt.
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)
20 February 2018
A security issue affects these releases of Ubuntu and its derivatives:
Several security issues were fixed in libvirt.
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)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to reboot your computer to make all the necessary changes.
Vulmon