Firefox 109: Manifest V3 support, security fixes and improvements

Firefox 109.0 Stable is the latest version of Mozilla's Firefox web browser. The new release of the open source web browser introduces support for Manifest V3 extensions, improved security on Windows devices, and security fixes.

firefox 109

All Firefox development channels and Firefox ESR, Extended Support Release, are updated around the same time. Firefox Beta and Developer channels move to version 110 and Firefox Nightly moves to version 111. Firefox ESR 102.7 is the latest version. Firefox for Android 109 will also be released today.

Executive Summary

Firefox 109.0 Stable is the first stable release that supports Manifest V3 extensions. These may now be installed from Mozilla's addons repository and other sources.
The new version fixes security issues. These will be published at a later point by Mozilla.

Firefox 109 download and update

Here are the official download locations:

Firefox 109.0 new features and improvements

Manifest V3 extensions

Firefox 109.0 is the first Stable release of Firefox that supports Manifest V3 extensions. Firefox continues to support Manifest V2 extensions. The update introduces a new extension button that lists all extensions and their site permissions, provided that these extensions are not pinned to the Firefox toolbar.

Selecting the cogwheel icon next to an extension displays the pin option to place it prominently on the Firefox toolbar. A right-click on pinned icons displays an option to unpin them. Unpinned extensions are moved to the Extensions menu automatically.

Mozilla reassured Firefox users that it would not follow Google's lead on making Manifest V3 the exclusive option for extensions. Google has been criticized heavily for the initial drafts that it put out, as it would have had a serious impact on content blockers, privacy extensions and some other types of extensions.

Google made changes to the Manifest V3, and while the company did address some critical issues, it did not resolve them all to the satisfaction of its critics.

Firefox will support Manifest V2 and V3 extensions, which means that users of the browser get the best of both worlds.

Other changes and fixes

The Code Guard exploit protection is now activate in the media playback utility process to improve security on Windows.
Firefox partitions storage in third-party contexts automatically "to align with other browsers and provide better Web compatibility".
The latest Colorways are no longer available in Firefox. Active and saved Colorway themes may still be accessed via about:addons > Themes. The themes were introduced in Firefox 106 as a temporary option.
The recently introduced Firefox View feature includes a new option to remove recently closed websites from the Firefox View history view.
Firefox View empty state messages for Tab Pickup and Recently Closed have been updated.
Spanish and Argentinian builds of Firefox come with a built-in dictionary now for the Firefox spellchecker.
Firefox's native HTML date picker may be used with just the keyboard now, which improves accessibility for screen reader users and users who prefer to use the keyboard.

Developer

Manifest V3 is supported. Extensions that use Manifest V3 may now be signed and released to Mozilla's Extensions Store.
Default Content Security Policy for Manifest V3 was updated to upgrade insecure requests by default to HTTPS. Extensions that require HTTP need to override the policy.
Property secretKeyLength was added to webRequest.SecurityInfo. It returns the length in bits of the secret key in the security properties of a web request.
Fixed two WebDriver bugs and improved functionality.
Scrollend API is now supported.
Content-visibility CSS property supports the auto value.

Enterprise changes

Mozilla lists three fixes and one policy change on the support page that lists the Firefox 109 changes for Enterprise:

Locking the HTTPS-Only preference did not disable the controls in the preferences.
Private browsing shortcuts are no longer created when the feature is disabled via policy. Does not apply to ESR.
New PrivatBrowsingShortcut option added to install to prevent the creation of the shortcut during installation. Does not apply to ESR.
The policy DisplayBookmarksToolbar has new options to show the toolbar on the New Tab page.

Known Issues

None listed.