Details about an Unbound vulnerability in Ubuntu 14.10 and Ubuntu 14.04 LTS, which has been found and corrected, have been published in a security notice by Canonical.
This is not a major problem, but this is a vulnerability and it needs to be addressed. Unbound (validating, recursive, caching DNS resolver) could have been made to consume resources if it got a special kind of network traffic.
"Florian Maury discovered that Unbound incorrectly handled delegation. A remote attacker could possibly use this issue to cause Unbound to consume resources, resulting in a denial of service," is noted in the security notice.
For a more detailed description of the problems, you can see Canonical's security notification. The problem can be corrected if you upgrade your system(s) to the latest libunbound2 and unbound packages. To apply the patch, you can simply run the Update Manager application, but you can also use the terminal.
Open a terminal and enter the following commands (you will need to be root and you will need Internet access):
sudo apt-get dist-upgrade