The new version of Firefox 157 is now available, and this new release marks the introduction of the browser's biggest visual redesign since 2021. The update comes alongside the new Long Term Support (LTS) versions 153.4.0, 140.17.0, and 115.42.0.
Firefox 157 addresses 76 vulnerabilities , 38 of which are classified as high severity and primarily related to critical memory management flaws. As a preventative measure, the browser now displays an explicit warning in the site information panel if it detects that the environment variable designed to store encryption keys is enabled, alerting the user to potential interception of network traffic by third-party applications.
Main new features of Firefox 157
The most notable change in this release is the default activation of the "Nova" user interface. This redesign abandons rigid edges in favor of rounded contours for tab buttons, drop-down menus, and the address bar.
Indentation and overall spacing have been adjusted for a cleaner, more balanced look, complemented by refreshed icons and high-contrast light and dark native themes. To better integrate the browser with web content, native JavaScript dialogs, date and color pickers, and autocomplete menus now automatically sync with the active page's color scheme. If an administrator needs to revert these visual changes, they can temporarily disable the corresponding preference from the advanced settings panel.
Responding to requests from users with small screens or those using split-screen setups, Mozilla has officially restored Compact Mode. This setting significantly reduces the vertical space occupied by the toolbars and top tab row, maximizing the area dedicated exclusively to reading web content.
Tab management has also been improved, with a new vertical tab sidebar . Access to advanced features like tab grouping and side-by-side view has been simplified and is now directly accessible from this panel. The manual option to show or hide the sidebar has been removed from the standard settings menu. Users who prefer the classic sidebar design can restore it by setting the "fake modernization" variable in the browser's internal settings—a compatibility option that will remain in place until the end of 2027.
Improvements in navigation, multimedia and security
Keyboard interaction has been optimized to speed up searches. Pressing the Tab key immediately shifts focus to the address bar text field , bypassing the search engine selection button, which remains accessible via a reverse key combination. Regarding built-in search engines, Amazon has been removed from the default list, though it can still be added manually. Additionally, Firefox Suggest's contextual recommendation service has expanded to 16 European countries, offering suggestions directly in the address bar.
Multimedia performance sees key improvements with the addition of hardware-accelerated decoding for the AV1 format in video calls via WebRTC. Annoying issues have been resolved, such as the inverted orientation of videos streamed from mobile devices, the dull display of 8-bit HDR videos on Windows, and audio and video desynchronization when repeatedly changing the playback speed on streaming platforms.
What's new for developers and Android
Web developers now have new CSS tools to refine the visual behavior of web pages. Support has been added for the "Specific Rules" feature within support queries, allowing developers to check browser compatibility with modern directives. Additionally, the over-scroll behavior properties now support a new value that facilitates a smooth transition to the parent element at the end of a content block, disabling visual bounce effects.
For Android users, navigation becomes more agile by allowing a return to previous search results by tapping the central search field, and quick deletion of downloads is enabled via a horizontal swipe gesture.
If you are interested in learning more, you can find the details at the following link.
How to install or update to Firefox 157
If you already have Firefox installed, the update should arrive automatically through your distribution's package manager in the next few days. However, if you want to get version 157 immediately without waiting for the official repositories , the best option is to use the official binary provided by Mozilla.
To install it from the binary on any Linux distribution (Ubuntu, Fedora, Arch, etc.), you can follow these steps in your terminal:
wget -O firefox.tar.bz2 "https://download.mozilla.org/?product=firefox-latest&os=linux64&lang=es-ES" sudo tar xjf firefox.tar.bz2 -C /opt/ sudo ln -sf /opt/firefox/firefox /usr/bin/firefox
If you prefer to use Snap packages (common in Ubuntu), you can force the update with:
Sudo Snap Refresh Firefox
For users who prefer Flatpak and Flathub, the update can be performed by running:
flatpak update org.mozilla.firefox
For users of Ubuntu, Linux Mint, and other Ubuntu derivatives, it's also possible to update Firefox via the official PPA . To do so, open a terminal and enter the following commands:
sudo add-apt-repository ppa:ubuntu-mozilla-security/ppa -y sudo apt-get update sudo apt install firefox
Finally, if you prefer to wait for it to arrive in your distribution's native repositories (DNF, Pacman), you just need to run your system's usual update command, although keep in mind that this can take anywhere from a few hours (on Arch) to several days (on Debian/Ubuntu).