...just don't try to download it from the Mac App Store.
"One arbitrary code execution vulnerability allows the injection of code after certain DOM event manipulations set the browser on a course to crash," The H Security reports. "A bug in the browser's use of SVG clipPaths could also lead Opera to execute arbitrary code by including specially prepared clipPaths in an SVG document. Other bug fixes in the new version correct problems with the browser's startup, image loading issues when navigating web sites, and communication errors on Facebook."
As Sophos' Graham Cluley notes, though, if you turn to Apple's Mac App Store to get the latest version of the browser, you'll find yourself downloading version 12.11 instead -- which means you'll be getting a browser that's two versions out of date. "The Mac App Store may be a convenient one-stop-shop for Mac users to get their software from, but it sure does a poor job at keeping that software up-to-date and ensuring that users are protected against the latest vulnerabilities," Cluley writes.