Canonical announced yesterday, June 20th, in a security notice, that an update for the default web browser in Ubuntu 12.04 LTS, Ubuntu 11.10, Ubuntu 11.04 and Ubuntu 10.04 LTS is now available.
Mozilla Firefox 13.0.1 fixes seven vulnerabilities found in the previous release of the popular web browser. To see detailed descriptions of the vulnerabilities fixed in Mozilla Firefox 13.0 click here.
To update your Firefox browser to version 13.0.1, use the "Software Updater" tool found under the Settings indicator. The following Ubuntu operating systems are supported: Ubuntu 12.04 LTS (Precise Pangolin), Ubuntu 11.10 (Oneiric Ocelot), Ubuntu 11.04 (Natty Narwhal), and Ubuntu 10.04 LTS (Lucid Lynx).