With the most recent update to Firefox 147, you can enjoy a number of new features and improvements. Safe Browsing v5 improves privacy protection, picture-in-picture mode for videos has learned a new trick, and the developers have once again fixed several security flaws.
Mozilla doesn’t plan to release Firefox 148 until six weeks from now, on February 24th. Then the question will arise again as to whether Mozilla will oncea gain extend update support for Firefox 115 for Windows 7 and 8 and macOS 10.12 to 10.14.
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What’s new in Firefox 147?
The picture-in-picture mode for videos, which has been available for years, can now be activated automatically as soon as the tab with the video is no longer in the foreground. When you bring the video tab back to the foreground, Firefox exits picture-in-picture mode. (You may have already observed similar behavior on YouTube.)
Also, the Mozilla developers have aligned the performance of video playback on AMD GPUs with that of Intel and Nvidia graphics.
Support for Safe Browsing v5, a Google feature, drastically reduces the number of cloud queries. With Safe Browsing v5, Firefox maintains a regularly updated local list of known fraudulent or dangerous websites. Firefox compares URLs to be accessed locally with this list, meaning that the address is not sent over to a cloud service.
Security fixes in Firefox 147
Mozilla lists at least 16 vulnerabilities that have been fixed in its Security Advisory 2026-01 report for Firefox 147, classifying six of the externally reported security vulnerabilities as high risk. Four of these relate to ways of breaking out of the browser sandbox. The vulnerabilities could be exploited to inject code and execute it on the system. No attacks on any of the vulnerabilities are known to date.
The last two entries in the report list an unspecified number of internally discovered vulnerabilities, which are summarized under CVE-2026-0891 and CVE-2026-0892. They also affect Firefox ESR and Thunderbird. Some are considered high risk, while others are only medium risk.
Firefox ESR and Tor Browser updates
In addition to Firefox 147.0, ESR versions 140.7.0 and 115.32.0 are also available, although the latter is only available for Windows 7 and 8.1 and macOS 10.12 to 10.14. In these versions, Mozilla’s developers have fixed the above-mentioned vulnerabilities that are already present in the well-established code of these browser generations.
The latest Tor Browser 15.0.4 is based on Firefox ESR 140.7 and includes the NoScript 13.5.7 extension. Tor Browser 13.5.27, based on Firefox ESR 115.32 and including NoScript 13.5.7, is only available for users of Windows 7 and 8.1 and macOS 10.12 to 10.14.
The Tor Project now hosts NoScript for its browser itself. This can be recognized by the fact that the NoScript version has the suffix “.1984,” like the current version 13.5.7.1984. (George Orwell sends his regards.) Otherwise, it’s identical to the version on Mozilla’s Add-ons store.
Thunderbird 147.0 and 140.7.0esr have also been released. Here, too, the developers have eliminated one or two security vulnerabilities that the mail program inherited from Firefox.