Version 154.0, first offered to Release channel users on August 18, 2026

Fixed an issue on macOS where closing a browser window could leave behind an invisible window that continued to capture mouse clicks over the area where it used to be.

Fixed an issue on Windows where an auto-hiding taskbar would not appear until the Firefox window had been minimized and restored after launch.

Fixed an issue where the Windows taskbar would appear in front of a full screen Picture-in-Picture window.

Fixed the Vertical Tabs sidebar staying visible in full screen mode. It now hides along with the toolbars and reappears when the cursor moves to the edge of the screen.

Fixed PDF documents not being scaled correctly in print preview when the Fit to Page Width option is used.

Various security fixes.

Video seeking is now significantly faster on all operating systems, making it quicker to jump to a point in a video.

Text selected in a PDF is now highlighted the same way as text on a web page, and the highlight color follows operating system settings such as high-contrast mode.

Firefox View is moving out of the toolbar by default for new profiles and for profiles where it hasn't been used recently. It can still be opened from List all tabs > View all tabs, or added back from the Customize toolbar menu.

You can find information about policy updates and enterprise-specific bug fixes in the Firefox for Enterprise 154 Release Notes.

The JSON Viewer now shows a breadcrumb path at the bottom for the selected entry.

Firefox now supports the text-box-trim and text-box-edge CSS properties, and the associated text-box shorthand. These properties control the leading space above and below text, enabling simpler and more consistent vertical spacing and alignment.

Firefox now supports the sibling-index() and sibling-count() CSS functions. These functions allow an element to be styled with calculations that use its index among its siblings and its total count of siblings (including itself), respectively.

Added a time picker user interface to <input type="time"> and <input type="datetime-local">, making selecting a time more accessible and intuitive.

Added support for the No-Vary-Search HTTP response header for the HTTP disk cache. Servers can now declare which URL query parameters are irrelevant to the response, allowing Firefox to reuse cached resources across parameter variations and improving cache hit rates.

Firefox now supports new Iterator.prototype.chunks and Iterator.prototype.windows methods that allow consuming an iterator as either overlapping or non-overlapping subsequences of configurable size.

Firefox now supports Iterator.prototype.includes(), allowing developers to check whether an iterator contains a given value without first converting it to an array.

Firefox now supports the Iterator.prototype.join method, which allows joining an iterator into a string, similar to Array.prototype.join.

For users with vertical tabs enabled, the sidebar may not persist across Firefox restarts. Vertical tabs can be re-enabled after the restart by clicking the sidebar toolbar button. We are currently working on a fix. (Bug 2065431)

When toolbars are hidden in fullscreen mode (the default on Windows and Linux), the vertical tabs sidebar does not appear when moving the cursor to the left edge of the screen. As a workaround, move the cursor to the top of the screen to reveal both toolbars and sidebar together. Alternatively, you can also right-click the toolbar and uncheck the Hide toolbars option. We are currently working on a fix. (Bug 2064638)

Following recent changes to Firefox’s Address Autofill logic, some users may experience autofill failures when auto-filling addresses. (Bug 2065145) Fixed in 154.0.1.

Following recent changes to Firefox’s password storage, some users may experience slower performance when Firefox accesses saved passwords. Users with a Primary Password enabled may also see unexpected password prompts, such as when starting Firefox or opening certain content. (Bug 2064411) Fixed in 154.0.1.

With the release of Firefox 154, we are pleased to welcome the developers who contributed their first code change to Firefox in this release, 32 of whom were brand new volunteers! Please join us in thanking each of these diligent and enthusiastic individuals, and take a look at their contributions:

• Ale Camara [:ale]: 2054573
• andra: 2022992, 2046118
• andrea.distefano: 1470011
• Anil Verman: 2040057
• Benoit: 2047559, 2049316, 2050403
• Brieuc Gommard: 2031346, 2049309
• christopher.staite: 2037813
• conor: 1988166
• Cornelius | CE student: 2046119
• Devin Rousso: 2052932
• Diego: 2018728
• elvyria: 2027522
• Gabe: 2049141
• Hagen: 2049264
• Hillwood Yang: 2048250
• Jaimukund Bhan: 2034642
• Kafji: 2051493
• Kometes: 1954212
• Luiz Henrique Vieira: 2050546
• Majed El-Barbari: 2040240
• Marcelo Camargo: 2009295
• Mayank Bansal: 2055744
• muhammad shaikh: 2016932
• Raimund Hook: 2050794
• Rebekah: 2052857
• Riza: 2044167
• Ronak Sheth: 2048099
• taylor: 1419649
• Tim McNulty: 2052560
• Yogeshdangal66: 2031348
• Zehui Xu: 2028402
• 占旭哲: 1992363