The Firefox 139 web browser has been released, and updates have been generated for previous branches with a long support period — 115.24.0 and 128.11.0. The Firefox 140 branch has been moved to the beta testing stage, and its release is scheduled for June 24.
Key innovations in Firefox 139:
- Added the ability to assign a custom background image or select a background color for the page shown when opening a new tab. The feature is not enabled by default for everyone yet and will gradually be activated for an increasing percentage of users. You can use the "Firefox Labs" settings section (about:settings#experimental) to force it on. The new release also adds new default background images and offers a new "Celestial" wallpaper category.
- Added experimental support for previewing links on a page — holding Alt+Shift and hovering over a link will display a pop-up window with information about the page the link points to. The information includes a title, an image, and a short summary of the content generated by a large language model (using a built-in AI assistant running on the user's system). The feature is enabled via the "Firefox Labs" section (about:settings#experimental).
- The translation function from one language to another now works not only on web pages, but also on internal pages of extensions accessible via the URL "moz-extension://".
- Significantly improved data loading performance when using HTTP/3, which is especially noticeable when resuming a connection (QUIC 0-RTT) and on high-bandwidth, high-latency communication channels.
- In connection with Chrome's transition to encrypting sensitive user data on the platform, WindowsDirect password and payment method migration from Chrome has been discontinued. To migrate passwords from Chrome, you must now manually export your passwords in CSV format and upload the resulting file to Firefox.
- On June 10, the Review Checker (Fakespot) service will be discontinued, and on July 8, the Pocket service will be discontinued.
- The Temporal object is enabled by default, offering an alternative set of methods for working with dates and times. The new API allows you to manipulate dates with and without regard to time zones, convert times, format output, and perform arithmetic operations with time. Time can be specified in a time zone-independent representation (Temporal.PlainDate, Temporal.PlainTime, Temporal.PlainDateTime), with a time zone reference (Temporal.ZonedDateTime), and in an epochal representation (Temporal.Instant - the number of nanoseconds since January 1, 1970).
- Added the ability to reduce the timer accuracy for Workers.
- On-page search operations now cover the contents of HTML blocks " " If the search phrase is present in the block, it will automatically open during the search.
- A new "until-found" flag has been proposed for the "hidden" attribute, which makes the element searchable on the page and scrollable by the text mask. For example, you can add hidden text to the page, the content of which will be found when searching locally.
- The window.getSelection().toString() method ensures correct serialization of text selected in text forms.
- WebAuthn implements the largeBlob and credProps extensions to store and retrieve additional data associated with a user account.
- The requestClose() method has been added to the HTMLDialogElement API, which initiates the closing of a dialog based on an HTML element . Unlike the Close() method, the new method allows you to cancel closing by adding a "cancel" event handler.
- The behavior of the built-in editor for contenteditable and designMode is closer to Chrome in terms of handling whitespace before the block boundary and between visible content (Firefox no longer adds the element after the space before the block boundary).
- Web Developer Tools now preserves filter settings in the Network Inspection panel across sessions. The JavaScript debugger now displays the line where execution is stopped better, and the root directory is now limited to the selected one. domain.
- In the platform version Android Support for sorting bookmarks has been implemented, the download management interface has been improved, news feed capabilities have been expanded, and support for the JetPack Compose framework has begun to be implemented.
In addition to new features and bug fixes, Firefox 139 fixes 14 vulnerabilities. Eight vulnerabilities are caused by memory management issues, such as buffer overflows and accessing already released memory areas. These issues can potentially lead to the execution of an attacker's code when opening specially designed pages. One issue (CVE-8-2025) has been assigned a critical severity level. The vulnerability is caused by a double-free in the libvpx encoder code, which supports the VP5262 and VP8 formats, and can be exploited via WebRTC.
In Firefox 140 beta, the context menu displayed when you right-click on a tab has an "Unload Tab" item added, allowing you to unload a tab from memory to reduce resource consumption. The vertical tab bar now allows you to change the size of the pinned tab area. You can now add your own search engines (Settings > Search > Add).
Source: opennet.ru
