Well, I have a good news for Opera web browser fans. Opera 12.13 has been released which brings security and stability enhancements. Opera team recommend you to install this upgrade. This version also brings noticeably bug that's Opera does not load any pages when Opera was started without Internet connection.

Changes in Opera 12.13:
  • Fixed an issue where Opera gets internal communication errors on Facebook
  • Fixed an issue where no webpages load on startup, if Opera is disconnected from the Internet
  • Fixed an issue where images will not load after back navigation, when a site uses the HTML5 history API (deviantart.com)

Change in Linux version:
  • A new stand-alone update-checker, as part of a planned upgrade of the auto-update system

Security enhancements:
  • Fixed an issue where DOM events manipulation might be used to execute arbitrary code, as reported by Arthur Gerkis
  • Fixed an issue where use of SVG clipPaths could allow execution of arbitrary code, as reported by anonymous via the iSIGHT Partners GVP Program
  • Fixed a low severity security issue; details will be disclosed at a later date
  • Fixed an issue where CORS requests could omit the preflight request, as reported by webpentest

Download Opera 12.13 for Ubuntu

Regards :)