Firefox's new third party cookie handling lands in Nightly

Martin Brinkmann
Mar 26, 2013
Updated • Mar 26, 2013

The Internet would not be the same without cookies. These little text snippets are used for a variety of purposes, most notable to store session information but also for preferences and other data that the site operators want their users to make use of across sessions. There is a dark side as well and it is firmly linked to the advertising and marketing world. Cookies are used to track users across websites they visit.

When you are connecting to a website cookies can be saved by first and third party connections made in the process. First party refers to the domain you are connecting to, which more often than not is used for site-specific operations across sessions. Third party refers to scripts that are loaded on the site that are executed from other domains, a Facebook like button or advertisement for example. These domains can save cookies to your computer as well.

Mozilla in February announced that it would provide users of its Firefox web browser with better third party cookie handling options. Yesterday, the new feature landed in the browser's latest Nightly build.

The major change here is that Firefox will only accept third party cookies from sites the user has visited in the past. The remaining third party cookies are blocked automatically in the browser.

So, if you are a regular on Facebook third party cookies from it will still be saved when you visit websites that implement one of its widgets on their site. In regards to websites that you do not visit, and most advertising networks probably fall in that category, you will notice that cookies do not get saved anymore on your system.

So what does it mean for users? The privacy is improved by this as fewer cookies will be saved on the user system. It needs to be noted that this won't eliminate tracking on the Internet as there are other means by which this can be achieved. Two options in this regard are Flash cookies and fingerprinting a user's system.

I suggest you clear all cookies in Firefox to remove all existing third party cookies from the browser before you start using the new feature.

To check how your version of Firefox is configured currently, click on the Firefox button at the top and then on options in the menu that opens up. From here, switch to Privacy and locate the "Accept cookies from sites" preference. Below that you find the new "Accept third-party cookies" menu.

  • Always will save all third party cookies.
  • From visited is the new preference that will save cookies from sites that you have visited.
  • Never will block all third party cookies.

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  1. Nebulus said on March 26, 2013 at 6:04 pm

    I’m blocking ads right now anyway and I don’t allow 3rd party cookies, so this new default value is not very important to me. There is a side effect though: the opt-out mechanism for some trackers involves storing a cookie on your computer, and blocking 3rd party cookies might stop this opt-out method from working.

  2. Oxa said on March 26, 2013 at 5:39 pm

    FEWER cookies will be saved, not “less cookies”.

  3. Keith said on March 26, 2013 at 2:06 pm

    Funny how this works. Abine’s Do Not Track blocked FIVE trackers from this site. Nuf said?

  4. DanTe said on March 26, 2013 at 12:43 pm

    Besides NoScript, I use Self Destructing Cookies and Better Privacy. All found from articles here.

  5. Virtualguy said on March 26, 2013 at 10:25 am

    I suspect this will cause more sites (especially those that receive a large percentage of their traffic from FF browsers) to use Flash cookies.

    1. Doc said on March 26, 2013 at 10:47 am

      That’s OK…I use NoScript and Flash is blocked by default unless I allow the origin site to load it.

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