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Extensions in Firefox 86

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Firefox 86 will be released on February 23, 2021. We’d like to call out two highlights and several bug fixes for the WebExtensions API that will ship with this release.

Highlights

  • Extensions that have host permissions for tabs no longer need to request the broader “tabs” permission to have access to the tab URL, title, and favicon URL.
  • As part of our work on Manifest V3, we have landed an experimental base content security policy (CSP) behind a preference in Firefox 86.  The new CSP disallows remote code execution. This restriction only applies to extensions using manifest_version 3, which is not currently supported in Firefox (currently, only manifest_version 2 is supported). If you would like to test the new CSP for extension pages and content scripts, you must change your extension’s manifest_version to 3 and set extensions.manifestv3.enabled to true in about:config. Because this is a highly experimental and evolving feature, we want developers to be aware that extensions that work with the new CSP may break tomorrow as more changes are implemented.

Bug fixes

  • Redirected URIs can now be set to a loopback address in the identity.launchWebAuthFlow API. This fix makes it possible for extensions to successfully integrate with OAuth authentication for some common web services like Google and Facebook. This will also be uplifted to Firefox Extended Support Release (ESR) 78.
  • Firefox 76 introduced a regression where webRequest.StreamFilter did not disconnect after an API, causing the loading icon on tabs to run persistently. We’ve also fixed a bug that caused crashes when using view-source requests.
  • The zoom levels for the extensions options pages embedded in the Firefox Add-ons Manager (about:addons) tabs should work as expected.
  • Now that the tabs hiding API is enabled by default, the extensions.webextensions.tabhide.enabled preference is no longer displayed and references to it have been removed.

As a quick note, going forward we’ll be publishing release updates in the Firefox developer release notes on MDN. We will still announce major changes to the WebExtensions API, like new APIs, significant enhancements, and deprecation notices, on this blog as they become available.

Thanks

Many thanks to community members Sonia Singla, Tilden Windsor, robbendebiene, and Brenda Natalia for their contributions to this release!

One comment on “Extensions in Firefox 86”

  1. Thierry wrote on

    Do you have somewhere a page with what is planned for Manifest V3 in Firefox? Maybe with a timeline?

    This blog post https://blog.mozilla.org/addons/2019/09/03/mozillas-manifest-v3-faq/ is now old. An update would help us a lot, to anticipate how we will support Firefox once Chrome and Edge have switched to MV3.