Firefox 158 Launches AI Form Filling and Patches 77 Security Flaws
Mozilla ships major security patches alongside JPEG XL support and smart automation tools.
1Firefox 158 Deployment Overview
Mozilla has officially released Firefox 158 across Windows, macOS, Linux, and Android ecosystems. Following the Nova interface refresh introduced in version 157, this release prioritizes foundational technical capabilities. It combines new browser utility features with substantial security hardening across both standard and Extended Support Release release branches.
2AI Smart Windows Feature
The headline end-user capability is the new AI-driven Smart Windows utility designed to accelerate form completion across web pages. Mozilla is initiating this rollout gradually, meaning access will stage over time rather than deploying universally on launch day. This mechanism targets streamlined data entry for repetitive web workflows.
3Enhanced PDF Rendering Capabilities
Firefox 158 incorporates structural upgrades to its internal document generation pipeline. Saving web pages as PDF files now produces documents with improved accessibility compliance, reducing barriers for assistive technologies. Mozilla also corrected multiple legacy rendering shortcomings that previously degraded complex layout fidelity during export workflows.
4Native JPEG XL Integration
Following an evaluation period within Firefox Labs since June, the browser now provides production support for the JPEG XL image format. JPEG XL delivers superior compression efficiency compared to legacy standards like JPEG, PNG, and WebP, maintaining competitive visual fidelity while minimizing bandwidth overhead for modern web delivery.
5Extensive Vulnerability Patch Scope
Mozilla addressed 77 distinct security flaws in this release advisory, with 37 discovered by external security researchers. OpenAI researcher Amy Burnett contributed nine independent vulnerability submissions. The patch set contains 30 high-risk, 33 medium-risk, and 14 low-risk designations, marking a significant maintenance cycle for core browser components.
6Critical Exploitation Vectors Addressed
The security advisory highlights 24 use-after-free flaws, several of which could allow arbitrary code execution under specific conditions. Crucially, engineers remediated eight distinct vulnerabilities that attackers could leverage to execute sandbox escapes. These patches isolate untrusted web content from gaining broader operating system privileges.
7Extended Support Release Maintenance
Alongside the stable build, Mozilla published ESR versions 153.5.0 and 115.43.0, backporting relevant vulnerability patches to legacy codebases. Firefox 153.5.0 received 61 security fixes, while version 115.43.0 resolved 17 flaws. Version 115 remains specifically designated for legacy operating systems like Windows 7, Windows 8.1, and macOS 10.12-10.14.
8Enterprise Support Lifecycles Ahead
Legacy platform support for Firefox ESR 115 is scheduled to persist until March 2027, maintaining a secured footprint on retired operating systems. Meanwhile, Firefox ESR 140 concluded its maintenance cycle on September 29th. Upstream development continues toward the next release milestone, with Firefox 159 planned for October 27th, 2026.
Original article: PCWorld — Firefox 158 Launches AI Form Filling and Patches 77 Security Flaws