Created primarily to make it more convenient for users to review sites over and over again, the rather raw technology has been used time and again to track users on the sites they visit. Browser makers are rallying to fight such privacy breaches and the latest version of Firefox is designed to block another type of cookie.
Focused on cross-site tracking cookies, those that follow you even after you leave the original web page that generated it. Mozilla, however, names yet another type of cross-site tracking which he calls “Supercookie”, although that could also be called “zombie cookie” as well. In addition to tracking users and registering them by fingerprint, these cookies are known to hide in other parts of the browser and are not cleared with other normal cookies. The supercookies also take advantage of Firefox’s caching mechanism which attempts to reduce bandwidth and data time by reusing images or other shared or embedded resources across different sites. unique identifier on one site which can then be verified again on another site when the same cached image is used.
Mozilla’s solution is to partition the Firefox network state and local cache per site from version 85, which means that each site will now have its own image cache, for example, which is only reused when visiting the same site but not when switching to another site using the same image. This has the effect of isolating Supercookies, but Mozilla admits that it has very little effect on page load times because of this.
Firefox 85 also marks the end of Adobe Flash, something that has been going on for years. It won’t play Flash content anymore and won’t offer an option to re-enable it, and you may forget to downgrade to an older version of Firefox to get around this as the Flash plug-in itself has already stopped working at this point.