14 DAY TRIAL // Canonical have announced that the latest Firefox 39.0.3 has been uploaded to the repositories for the users of Ubuntu 15.04, Ubuntu 14.04 LTS, and Ubuntu 12.04 LTS.
The Ubuntu maintainers are not usually this quick to upload the latest Firefox version, even if it's a package that ships by default with the distribution. The fact that they chose to make available just a day after its release by Mozilla means that the security issue that were corrected are quite important.
"Cody Crews discovered a way to violate the same-origin policy to inject script into a non-privileged part of the PDF viewer. If a user were tricked into opening a specially crafted website, an attacker could exploit this to read sensitive information from local files" reads the security notice.
More details about this vulnerability that was identified in the Firefox browser can be found in our original report. To fix this issue, Ubuntu users need to upgrade as soon as possible. This can be done in a couple of ways, either with the dedicated upgrade tool or by using the terminal.
If you decide to use the terminal these are the commands that you have to enter (root is required):
sudo apt-get dist-upgrade