Firefox 140 improves web translation performance and pinned tabs

Firefox’s latest update brings the browser to the 140 version with various new features and improvements. For example, the internal translation function is more economical in resources and the pinned tabs are more flexible. Developers have also set several security vulnerabilities. Firefox ESR and Tor Browser have also received security updates.

Mozilla plans to release the Firefox versions 141 and Firefox ESR 140.1, ESR 128.13 and ESR 115.26 on July 22, 2025.

What’s new in Firefox 140?

Firefox’s local translation function initially only translates the content currently visible in the browser window. It is only when you scroll through the previously invisible sections of a page that will then translate this content. This reduces the consumption of resources and improves performance.

If you use the vertical tabs introduced with Firefox 136 in combination with pinned tabs, you can now keep plus (or less) pinned tabs. All you have to do is move the separator line.

Firefox is now supporting even more search engines you can add. To do this, right -click in the search field of a website (supported) and select “Add a search engine” from the context menu. For Firefox users in the United States on version 139 and more, Mozilla added the perplexity of the AI ​​search engine to the standard selection in mid-June to user demand.

Security updates in Firefox 140

The Mozilla security council in 2025-51 shows 17 vulnerabilities fixed for Firefox 140. Mozilla classifies one of the vulnerabilities reported outside as high risk. It is a vulnerability of use after without (CVE-201025-6424) in the Fontfaceset API. An attacker could exploit it by causing a crash that would perform the code injected.

Five internal discovery vulnerabilities, summarized under CVE-2025-6436, are also considered a high risk. All other vulnerabilities that Mozilla developers have set in Firefox 140 are classified as an average or low risk. One of them, CVE-2025-6431, only affects Firefox for Android.

Firefox ESR and Tor Browser updates

Firefox 140 is the latest standard version for Firefox ESR. Firefox ESR 140 will initially be identical to the ordinary Firefox 140, but it will only receive security updates and significant bug corrections, no new features.

Mozilla will support Firefox ESR 128 and ESR 140 in parallel until August 19, when this transition phase will end. Firefox ESR 115 is also planned to end the support for the August update, unless Mozilla decides to extend the deadline again (to be announced in August).

Mozilla has updated its long-term versions Firefox ESR 128 and ESR 115 and has also corrected certain vulnerabilities, namely the fabric factory mentioned above. Five vulnerabilities were set in Firefox ESR 128.12.0 and two in Firefox ESR 115.25.0.

The updated navigator 14.5.4 is based on Firefox ESR 128.12.0 and is delivered with the new version 13.0.8 of NOSCRIPT. The TOR developers indicate that they also have Firefox 140 safety fixes. An update for the TOR 13.5 browser in version 13.5.19 is also available if you use Windows 7 / 8.1 or MacOS 10.12 to 10.14. The browser TOR 13.5.19 is based on Firefox ESR 115.25.0 and also includes the NOSCRIPT 13.0.8.