Firefox 85

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Older versions of Firefox

Mozilla Firefox 85 was released today with supercookie protection to block hidden trackers from tracking Firefox users' activity while browsing the Internet.

Windows, Mac, and Linux desktop users can upgrade to Firefox 85 by going to Options -> Help -> About Firefox. The browser will automatically check for the new update and install it when available.

With the release of Firefox 85, all other Firefox development branches have also moved up a version bringing Firefox Beta to version 86 and the Nightly builds to version 87.

You can download Firefox 85 from the following links:

If the download links above haven't yet been updated to download the latest Firefox version, you can manually download it from Mozilla's official FTP release directory.

Below you can find the major changes and improvements in Firefox 85 — if you want to read the full release notes, you can do so here.

Built-in protection from supercookies

'Firefox now protects you from supercookies, a type of tracker that can stay hidden in your browser and track you online, even after you clear cookies,' the released notes read.

'By isolating supercookies, Firefox prevents them from tracking your web browsing from one site to the next.'

Mozilla has been fighting against online tracking and adtech companies since 2018 by enabling Firefox to automatically block cookies from known trackers via enhanced tracking protection enabled by default.

Firefox 85.0.2

Starting with Firefox 72 launched one year ago in January 2020, the web browser is also auto-blocking scripts designed by known fingerprinting companies for browser fingerprinting via cross-site tracking.

With the release of Firefox 85, Mozilla's browser is isolating caches and network connections for each visited website. This makes supercookies useless for tracking users while browsing between sites.

'In short, supercookies can be used in place of ordinary cookies to store user identifiers, but they are much more difficult to delete and block,' Mozilla's Steven Englehardt and Arthur Edelstein explained.

'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.'

Other new features and changes in Firefox 85

The other highlight of this Firefox release is the removal of Adobe Flash support. The new Firefox version ships without Flash support, thus improving the browser's performance and security.

Adobe's Flash Player reached its end of life (EOL) on January 1, 2021, after being a constant security risk over the years.

Adobe is displaying alerts on Windows computers advising users to 'immediately' uninstall Flash Player from their systems and has removed all Flash Player download pages from its websites.

Starting with this Firefox release, there is no setting available for users who want to re-enable Flash support.

Firefox 85 also allows users to remove all saved logins with a single mouse click and improves bookmark management.

Fixes high severity vulnerabilities

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Firefox 85 also addresses multiple security vulnerabilities with severity ratings ranging from low to high severity.

Firefox 85 Download

The most severe ones, CVE-2021-23964 and CVE-2021-23965, are caused by memory safety bugs that would have allowed attackers to execute arbitrary code remotely on systems running vulnerable Firefox versions.

'Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code,' Mozilla explained.

Firefox 85 Problems

Mozilla also fixed a vulnerability (tracked as CVE-2021-23955) that could have enabled attackers to launch clickjacking attacks across tabs through misusing requestPointerLock.

The full list of vulnerabilities includes:

• CVE-2021-23953: Cross-origin information leakage via redirected PDF requests
• CVE-2021-23954: Type confusion when using logical assignment operators in JavaScript switch statements
• CVE-2021-23955: Clickjacking across tabs through misusing requestPointerLock
• CVE-2021-23956: File picker dialog could have been used to disclose a complete directory
• CVE-2021-23957: Iframe sandbox could have been bypassed on Android via the intent URL scheme
• CVE-2021-23958: Screen sharing permission leaked across tabs
• CVE-2021-23959: Cross-Site Scripting in error pages on Firefox for Android
• CVE-2021-23960: Use-after-poison for incorrectly redeclared JavaScript variables during GC
• CVE-2021-23961: More internal network hosts could have been probed by a malicious webpage
• CVE-2021-23962: Use-after-poison in nsTreeBodyFrame::RowCountChanged
• CVE-2021-23963: Permission prompt inaccessible after asking for additional permissions
• CVE-2021-23964: Memory safety bugs fixed in Firefox 85 and Firefox ESR 78.7
• CVE-2021-23965: Memory safety bugs fixed in Firefox 85