Opera Software releases Opera 12.15 for Windows, Linux and Mac incorporating visual enhancement and technical improvements. This is meant to fix a number of bugs, and also improve this version’s stability and security.

Here is the list of favorite under-the-hood improvements in this release.
- Fixed an issue where the search bar’s default engine could be overridden by third-party apps
- Fixed a moderately severe issue
- Added safeguards against attacks on the RC4 encryption protocol
- Fixed an issue where cookies could be set for a top-level domain
Full details about what changes are in this build are available on Opera Changelogs.
Source: Opera Officials