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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.