14 DAY TRIAL // Canonical announced that quite of few LibTIFF vulnerabilities have been corrected for Ubuntu 14.10, Ubuntu 14.04 LTS, Ubuntu 12.04 LTS, and Ubuntu 10.04 LTS distros.
LibTIFF stands for Tag Image File Format (TIFF) library and it seems that LibTIFF could have been made to crash if it opened a specially created file.
"William Robinet discovered that LibTIFF incorrectly handled certain malformed images. If a user or automated system were tricked into opening a specially crafted image, a remote attacker could crash the application, leading to a denial of service, or possibly execute arbitrary code with user privileges," reads the security advisory.
This is just one of the issues that have been corrected. For a more detailed description, you can see Canonical's security notification. Users are advised to upgrade their systems as soon as possible.
In general, a standard system update will make all the necessary changes and a reboot it's not required in order to complete the process. Please keep in mind that Ubuntu 10.04 LTS has almost reached end of life and this is likely one of the last updates for it.
You can also use the terminal to update the system. Just enter these commands in a terminal near you:
sudo apt-get dist-upgrade