Firefox 151 Launches With Privacy Upgrades, VPN Improvements and 30+ Security Fixes

Mozilla Firefox version 151 is now rolling out for Windows, macOS, Linux and Android, bringing expanded privacy protections, improvements to the built-in PDF tools and fixes for more than 30 security vulnerabilities.

Mozilla has also released updated Extended Support Release (ESR) versions for users on older systems and enterprise deployments.

Firefox VPN Feature Gains Multiple Location Options

One of the most notable additions in Firefox 151 involves Mozilla’s integrated VPN feature, which first appeared in Firefox 149.

Users can now choose between several virtual VPN locations, including the United States, Canada, the United Kingdom, France and Germany.

The VPN feature currently remains limited to users within those same supported countries and requires a free Mozilla account to activate.

Mozilla says users receive up to 50GB of free VPN traffic per month under the current implementation.

The location-selection functionality is reportedly rolling out gradually.

Private Browsing and Fingerprinting Protection Improved

Firefox 151 also introduces a new one-click option for resetting private browsing sessions without closing the entire browser window.

The feature immediately clears session history and starts a fresh private session.

Mozilla additionally says the browser’s anti-fingerprinting protections have been upgraded, reducing advertiser tracking effectiveness by approximately 14 percent overall and by up to 50 percent on macOS systems.

Fingerprinting techniques are commonly used by advertisers and tracking companies to identify users based on hardware, browser and system characteristics even without traditional cookies.

PDF Editor Gains File Merging Support

Firefox’s built-in PDF viewer and editor continues expanding functionality.

Users can now merge multiple PDF documents directly inside the browser without relying on external software.

Mozilla also moved the browser’s internal translation page into the standard “More Tools” menu, making translation features easier to access.

Linux users additionally gain new options for locally backing up and restoring Firefox profiles across platforms.

Over 30 Security Vulnerabilities Patched

Mozilla’s Security Advisory 2026-46 lists more than 30 patched security vulnerabilities in Firefox 151.

Among them, four externally reported flaws are classified as high severity, including CVE-2026-8945, which involves a potential browser sandbox escape vulnerability.

Mozilla says 28 of the vulnerabilities were discovered and reported by external security researchers.

Additional fixes address medium- and low-severity flaws alongside several internally discovered memory-management vulnerabilities.

ESR Versions and Thunderbird Also Updated

Mozilla also released updated ESR builds including:

• Firefox ESR 140.11.0
• Firefox ESR 115.36.0

The ESR 115 branch continues supporting older operating systems such as Windows 7, Windows 8.1 and older macOS releases through August 2026.

Updated versions of Mozilla Thunderbird are also expected shortly, inheriting many of the same security fixes included in Firefox 151.