Both Firefox and Chrome have proven very good and very fast at fixing these kinds of security issues. There's already a patch out for both browsers that completely seals the leak. Your browser may have even updated automatically. If you have Firefox version 32.0.3 or Chrome version 37.0.2062.124, you're safe. It's easy to check which version you have:
Firefox: Click the three horizontal lines in the top right to bring up the menu. Then click the little question mark at the bottom of the pop-up menu. Click "About Firefox." You'll see your version right there. Also, if Firefox is out of date, just opening this window will automatically start the update process. Neat!
Chrome: Check out the three horizontal lines in the top right. If you're browser is out of date, these will be orange or red. If they're orange or red, you'll see a line in the menu that says "Update Google Chrome." Click that. Easy!
I always, always keep my browsers up to date. You should too! If you don't know what browser you have or how to update it, click here to read a helpful tip.