Mozilla once again confirmed that it would start blocking all cookies from third-party advertisers by default in Firefox. However, the company has walked back on its plans as it continues to test the system.
Brendan Eich from Mozilla said that the patch needed more testing and data before it is launched. Eich said, “The idea is that if you have not visited a site (including the one to which you are navigating currently) and it wants to put a cookie on your computer, the site is likely not one you have heard of or have any relationship with”.
Eich also cited false positives, cookies from a site user visits being blocked as it has multiple addresses and false negatives, in which an ad is clicked accidentally or a formerly trusted site starts adding cookies. The new patch has been developed by Jonathan Mayer, a Stanford law student and was initially set to be deployed in Firefox 22.
For now, no timeline has been set for its release, but Eich will be providing an update in the next six weeks. Advertisers who depend on third-party cookies to target users across the cites criticized Mozilla for the move.