What’s new in Firefox 158?
Following the new Nova design introduced in Firefox 157, some technical improvements are now being implemented. The AI-powered Smart Windows feature is designed to help users fill out forms faster. It is being rolled out gradually, so it will not be available to all users immediately.
Another improvement involves saving web pages as PDF files. Firefox now generates more accessible PDF files (i.e. fewer barriers) and other shortcomings in PDF rendering have been fixed.
Firefox now supports the JPEG XL image format, which has been running as a Firefox Labs experiment since June. Image compression with JPEG XL is more efficient than older formats such as JPEG, PNG, and WebP, while maintaining comparable image quality.
Security flaws fixed in Firefox 158
In the security advisory for Firefox 158, Mozilla lists 77 security flaws that have been fixed, 37 of which were discovered and reported by third-party security researchers (OpenAI’s Amy Burnett stands out with 9 reports).
Mozilla classifies 30 vulnerabilities as “high risk,” 33 as “medium risk,” and 14 as “low risk.” Among the security vulnerabilities fixed are 24 use-after-free (UAF) flaws, some of which can be exploited to execute malicious code. Eight vulnerabilities can be exploited to escape the browser sandbox.
Firefox ESR Updates
In addition to Firefox 158.0, ESR versions 153.5.0 and 115.43.0 are now also available. However, the latter is only available for Windows 7 and 8.1 and macOS 10.12 to 10.14, and will remain so until March 2027.
