Firefox 157 is out for Windows, macOS, Linux, and Android and the biggest change in this version is the new Nova design, which brings a more modern look to the browser. Mozilla has also fixed over 70 security vulnerabilities, and updates are also available for the Firefox ESR versions.
The release of Firefox 158 is scheduled for October 13th, 2026.
What’s new in Firefox 157?
Now that Firefox has adopted a two-week release cycle, major new features are growing fewer and farther between. With Firefox 157, the focus is on the new Nova design, which has heavily rounded corners and subtle color gradients on surfaces. You’ll find 12 themes, each in light and dark variants.
Mozilla has also brought back the popular Compact Mode, which groups elements together to save space—great for smaller screens.
You can learn more about the Nova redesign and what it entails in this announcement post by the Mozilla team.
Security fixes in Firefox 157
In the security advisory for Firefox 157, Mozilla lists 76 vulnerabilities that have been fixed, 30 of which were discovered and reported by external security researchers.
Mozilla classifies 38 vulnerabilities as high risk, 29 as medium risk, and nine as low risk. Among them, 32 are use-after-free (UAF) vulnerabilities, some of which could be exploited to inject and execute code, and 15 of which could be exploited to escape the browser sandbox.
Firefox ESR updates
In addition to Firefox 157, Firefox ESR releases 153.4.0, 140.17.0, and 115.42.0 are also now available. However, the latter are only available for Windows 7 and 8.1 and macOS 10.12 to 10.14 until March 2027.
In the ESR versions, Mozilla has fixed the aforementioned vulnerabilities that were also present in the code of these earlier browser generations. That amounts to 62 vulnerabilities in Firefox 153.4.0, 43 in Firefox 140.17, and 31 in Firefox 115.42.
Firefox ESR 140 received its final update on September 29th. In two weeks, this version will finally be replaced by Firefox ESR 153. If you haven’t already done so, it’s time to start planning the switch.
