Firefox 85 removes Flash and adds protection against supercookies

Mozilla has released today Firefox 85 to the stable channel, a new version of its beloved browser that removes support for the Adobe Flash Player plugin but also boosts privacy protections by adding more comprehensive defenses against “supercookies.”

The removal of the Flash plugin comes after Mozilla announced its intention to drop Flash in July 2017 as part of a coordinated industry-wide Flash deprecation and End-of-Life plan, together with Adobe, Apple, Google, Microsoft, and Facebook.

The EOL date was set to December 31, 2020, a date after which Adobe agreed to stop providing updates for the software.

Firefox now joins Chrome and Edge, both of which removed support for Flash earlier this month with the release of Chrome 88 and Edge 88.

Network partitioning and supercookies protection

But even if Firefox 85 is the first version that ships without the much-maligned Flash plugin, the bigger feature in this release is “network partitioning.”

First reported by ZDNet last month, the network partitioning feature works by splitting the Firefox browser cache on a per-website basis, a technical solution that prevents websites from tracking users as they move across the web.

In a blog post today, Mozilla said this new feature has effectively blocked the use of supercookies inside Firefox going forward.

“Supercookies can be used in place of ordinary cookies to store user identifiers, but they are much more difficult to delete and block,” Mozilla said today.

“Over the years, trackers have been found storing user identifiers as supercookies in increasingly obscure parts of the browser, including in Flash storage, ETags, and HSTS flags.

“The changes we’re making in Firefox 85 greatly reduce the effectiveness of cache-based supercookies by eliminating a tracker’s ability to use them across websites,” the browser maker said.

Mozilla said that while they expected a big impact on website performance after splitting the Firefox cache, internal metrics show that the impact was minimal.

“Our metrics show a very modest impact on page load time: between a 0.09% and 0.75% increase at the 80th percentile and below, and a maximum increase of 1.32% at the 85th percentile,” Mozilla said.

The browser maker viewed this performance impact as acceptable for improving overall user privacy.

Other changes

But there are also other features that shipped with Firefox 85 today. The first is a change in how bookmarks are saved inside Firefox.

Starting with this version, Firefox now remembers where users saved their last bookmark and saves all other bookmarks to the same location. 

Furthermore, Firefox has also added a bookmarks folder to the bookmarks toolbar. This last feature caused some problems last week, when some Firefox users saw it in their browsers, but without an easy way of disabling it. With Firefox 85, removing that folder from the bookmarks toolbar is possible via a right-click menu option.

In addition, Firefox 85 also ships with a button to remove all saved credentials, which could be a very useful feature in case users need to clear a Firefox installation and make it available for other users.

Other changes are detailed in the Firefox 85 changelog here, while security updates are listed here.