On October 10th, in a security notice Canonical published details about a QEMU vulnerability for its Ubuntu 12.04 LTS, Ubuntu 11.10, Ubuntu 11.04, Ubuntu 10.04 LTS, and Ubuntu 8.04 LTS operating systems.
According to Canonical, Bind could be made to crash if it received specially crafted network traffic. It was discovered that Bind incorrectly handled certain specific combinations of RDATA. A remote attacker could use this flaw to cause Bind to crash, resulting in a denial of service.
The security flaws can be fixed if you upgrade your system(s) to the latest bind9, specific to each operating system. To apply the update, run the Update Manager application.
In general, a standard system update will make all the necessary changes. A system restart won't be necessary to implement the changes, but users have to restart the virtual machine.