Introducing Site Isolation in Firefox

<!DOCTYPE html> <html lang="en-US" dir="ltr" class="no-js"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="license" href="#license"> <link rel="profile" href="https://gmpg.org/xfn/11"> <link rel="shortcut icon" type="image/png" href="https://blog.mozilla.org/security/wp-content/themes/frontierline/img/favicon.png">   <meta name="title" content="Introducing Site Isolation in Firefox – Mozilla Security Blog"> <meta property="og:site_name" content="Mozilla Security Blog"> <meta property="og:url" content="https://blog.mozilla.org/security/2021/05/18/introducing-site-isolation-in-firefox"> <meta property="og:title" content="Introducing Site Isolation in Firefox – Mozilla Security Blog"> <meta property="og:description" content="With Site Isolation enabled on Firefox for Desktop, Mozilla takes its security guarantees to the next level."> <meta property="twitter:title" content="Introducing Site Isolation in Firefox – Mozilla Security Blog"> <meta property="twitter:description" content="With Site Isolation enabled on Firefox for Desktop, Mozilla takes its security guarantees to the next level."> <meta name="twitter:card" content="summary"> <meta name='robots' content='index, follow, max-image-preview:large, max-snippet:-1, max-video-preview:-1' /> <meta name="blog-name" content="Mozilla Security Blog" />  <title>Introducing Site Isolation in Firefox - 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id="search" class="fm-search" method="get" action="https://blog.mozilla.org/security/"> <fieldset> <p> <label for="s">Search this site</label> <input type="search" value="" name="s" id="s"> <button type="submit" class="button button-minor">Search</button> </p> </fieldset> </form> </li> </ul> </nav> <main id="content"> <div class="content"> <article id="post-2743" class="post post-2743 type-post status-publish format-standard hentry category-announcements category-firefox category-security tag-firefox tag-security"> <header class="entry-header"> <div class="entry-tools"> <div class="categories"> <b>Categories:</b> <a href="https://blog.mozilla.org/security/category/announcements/" rel="category tag">Announcements</a> <a href="https://blog.mozilla.org/security/category/firefox/" rel="category tag">Firefox</a> <a href="https://blog.mozilla.org/security/category/security/" rel="category tag">Security</a> </div> </div> <h1 class="entry-title"> Introducing Site Isolation in Firefox </h1> <div class="entry-info"> <address class="vcard"> Anny Gakhokidze and Neha Kochar </address> <time class="date published" datetime="2021-05-18T08:47:25-07:00">May 18, 2021</time> </div> </header> <div class="entry-content"> <p>When two major vulnerabilities known as <a href="https://en.wikipedia.org/wiki/Meltdown_(security_vulnerability)">Meltdown</a> and <a href="https://en.wikipedia.org/wiki/Spectre_(security_vulnerability)">Spectre</a> were disclosed by security researchers in early 2018, Firefox promptly <a href="https://blog.mozilla.org/security/2018/01/03/mitigations-landing-new-class-timing-attack/">added security mitigations</a> to keep you safe. Going forward, however, it was clear that with the evolving techniques of malicious actors on the web, we needed to redesign Firefox to mitigate future variations of such vulnerabilities and to keep you safe when browsing the web!</p> <p>We are excited to announce that Firefox’s new Site Isolation architecture is coming together. This fundamental redesign of Firefox’s Security architecture extends current security mechanisms by creating operating system process-level boundaries for all sites loaded in Firefox for Desktop. Isolating each site into a separate operating system process makes it even harder for malicious sites to read another site’s secret or private data.</p> <p>We are currently finalizing Firefox’s Site Isolation feature by allowing a subset of users to benefit from this new security architecture on our Nightly and Beta channels and plan a roll out to more of our users later this year. If you are as excited about it as we are and would like to try it out, follow these steps:</p> <p><b>To enable Site Isolation on Firefox Nightly:</b></p> <ol> <li aria-level="1">Navigate to about:preferences#experimental</li> <li aria-level="1">Check the “Fission (Site Isolation)” checkbox to enable.</li> <li aria-level="1">Restart Firefox.</li> </ol> <p><b>To enable Site Isolation on Firefox Beta or Release:</b></p> <ol> <li aria-level="1">Navigate to about:config.</li> <li aria-level="1">Set `fission.autostart` pref to `true`.</li> <li aria-level="1">Restart Firefox.</li> </ol> <p>With this monumental change of secure browser design, users of Firefox Desktop benefit from protections against future variants of Spectre, resulting in an even safer browsing experience. If you aren’t a Firefox user yet, <a href="https://www.mozilla.org/firefox/new/">you can download the latest version here</a> and if you want to know all the technical details about Firefox’s new security architecture, you can read it <a href="https://hacks.mozilla.org/2021/05/introducing-firefox-new-site-isolation-security-architecture/">here</a>.</p> </div> <footer class="entry-tags"> <p><b>Tags:</b> <a href="https://blog.mozilla.org/security/tag/firefox/" rel="tag">Firefox</a>, <a href="https://blog.mozilla.org/security/tag/security/" rel="tag">Security</a></p> </footer> <footer class="fx-footer"> <h4>Browse fast. 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datetime="2024-06-05T06:05:31-07:00">June 5, 2024</time> </li> <li> <h5 class="entry-title"><a href="https://blog.mozilla.org/security/2023/12/06/mozilla-vpn-security-audit-2023/">Mozilla VPN Security Audit 2023</a></h5> <time class="date" datetime="2023-12-06T09:00:37-08:00">December 6, 2023</time> </li> <li> <h5 class="entry-title"><a href="https://blog.mozilla.org/security/2021/07/12/firefox-90-supports-fetch-metadata-request-headers/">Firefox 90 supports Fetch Metadata Request Headers</a></h5> <time class="date" datetime="2021-07-12T01:24:24-07:00">July 12, 2021</time> </li> <li> <h5 class="entry-title"><a href="https://blog.mozilla.org/security/2021/06/02/updating-gpg-key-for-signing-firefox-releases/">Updating GPG key for signing Firefox Releases</a></h5> <time class="date" datetime="2021-06-02T01:29:36-07:00">June 2, 2021</time> </li> <li> <h5 class="entry-title"><a href="https://blog.mozilla.org/security/2020/11/17/firefox-83-introduces-https-only-mode/">Firefox 83 introduces 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Introducing Site Isolation in Firefox - Mozilla Security Blog