On September 30, in a security notice, Canonical published details about libKDcraw vulnerabilities in its Ubuntu 12.04 LTS (Precise Pangolin) operating system.
According to Canonical, libKDcraw could have been made to crash if it opened a specially crafted file.
It has been discovered that libKDcraw incorrectly handled photo files. If a user or automated system were tricked into processing a specially crafted photo file, applications linked against libKDcraw could be made to crash, resulting in a denial of service.
For a more detailed description of the security problems, you can see Canonical's security notification.
The security flaws can be fixed if you upgrade your system(s) to the latest libkdcraw20, specific to each distribution. To apply the update, run the Update Manager application.
In general, a standard system update will make all the necessary changes. A system restart will not be necessary to implement the changes.