Details of the vulnerability in Unbound in Ubuntu 14.10 & Ubuntu 14.04 LTS, which has been identified and patched, were published in a Canonical announcement.

However, it is not a big problem, but it is a vulnerability and needs to be addressed. Exploiting this vulnerability (validating, recursive, caching DNS resolver) could lead to consuming system resources, with certain types of network traffic.
“ Florian Maury discovered that Unbound incorrectly handled delegation. A malicious user could potentially exploit this vulnerability to cause resource consumption, which could lead to a denial of service,” the security bulletin notes.
The security issue can be fixed by upgrading your system 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 type the following commands (you must be root and you must have access to the Internet):
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sudo apt-get update
sudo apt-get dist-upgrade
The update process is fast and all packages are retrieved quickly. In general, a standard system update will make all the necessary changes. Restarting the operating system is not necessary.
