The release of Firefox 146 brings several enhancements and updates to the browser. Users gain access to a fresh data preservation option that operates independently of account syncing, along with simplified management of Firefox Labs trials. Additionally, a series of security issues have been addressed in this version.
Mozilla has scheduled the rollout of Firefox 147 for January 13, 2026, aligning with Microsoft's upcoming Patch Tuesday event.
Windows users benefit from a new data backup capability in Firefox 146, designed primarily to facilitate the transition from Windows 10 to Windows 11. This tool allows saving browser information to a local drive or OneDrive without needing to sign into an account, ensuring seamless access on the upgraded system. The feature is being deployed in phases, so availability varies across installations.
Determining location for the weather display on Firefox's start page requires user permission in the European Union, reflecting the browser's strong emphasis on privacy. This opt-in approach for geolocation data is also rolling out progressively to users.
Experimental functionalities in Firefox can now be enabled without the need to share telemetry information, offering greater control over data usage.
According to the 2025-92 Security Advisory from Mozilla, at least 13 vulnerabilities have been resolved. Among the five high-severity issues reported externally, two stem from flaws in the JavaScript Just-In-Time compiler. A use-after-free error in the WebRTC module has likewise been corrected.
The advisory's final two items cover an undisclosed count of internally identified weaknesses, consolidated under CVE-2025-14332 and CVE-2025-14333. These are rated as medium severity, with no exploitation methods documented to date.
Alongside the standard Firefox 146.0, extended support release variants 140.6.0 and 115.31.0 have been issued. The latter is limited to Windows 7, 8.1, and macOS versions 10.12 through 10.14. These updates incorporate fixes for the vulnerabilities affecting their respective codebases, including some longstanding ones.
The updated Tor Browser 15.0.3 relies on Firefox ESR 140.6 and includes the NoScript 13.5.2 extension. For legacy systems on Windows 7, 8.1, or macOS 10.12 to 10.14, Tor Browser 13.5.26 uses Firefox ESR 115.31 paired with NoScript 13.5.2. The Tor Project now maintains its own version of NoScript, indicated by the ".1984" suffix (13.5.2.1984), which matches the add-on available via Firefox's store.
Thunderbird 146.0, now supporting Exchange integration, and the 140.6.0 ESR edition have been made available. These updates address one or two security weaknesses carried over from the Firefox codebase.