Overview of Firefox 151
The latest version of Firefox for Windows, macOS, Linux, and Android introduces significant improvements to user privacy, a revamped PDF viewer, and updates to the built-in VPN feature. Additionally, Mozilla has addressed over 30 security vulnerabilities in this release. Updates are also rolling out for the Extended Support Release (ESR) versions, ensuring long-term stability for enterprise users.
Privacy and VPN Enhancements
Firefox 151 builds on the VPN feature first introduced in version 149. Users in the United States, Canada, the United Kingdom, France, and Germany can now choose from multiple virtual locations. To access the VPN, you need a free Mozilla account, and you receive 50 GB of data per month. The location selection is being phased in gradually.
Private browsing gets a notable upgrade: you can now clear an entire session with a single click, eliminating the need to close the browser window. This action starts a fresh private session without any history. Mozilla also claims improved anti-fingerprinting measures in Firefox 151, reducing the number of users identifiable through standard fingerprinting techniques by 14 percent overall—and by up to 50 percent on macOS alone.
Enhanced PDF Viewer and Navigation Tools
The built-in PDF viewer/editor gains a new capability: merging multiple PDF files into one document. This feature adds to existing editing options, making Firefox a more powerful tool for document management.
The New Tab page receives additional background images and is prepared for upcoming features scheduled before the release of Firefox 152 on June 16. Users can also access the internal translation page (about:translations) more easily through the More Tools menu. Linux users can now back up their Firefox profiles locally and restore them across different platforms.
Security Fixes in Firefox 151
Mozilla’s Security Advisory 2026-46 for Firefox 151 lists over 30 fixed vulnerabilities. Of these, 28 were reported by external researchers. Four are classified as high risk, including a potential sandbox escape (CVE-2026-8945). Eleven are medium risk, and the rest are low risk. The final three entries address internally discovered memory management errors.
Keeping your browser updated is crucial for security. For comprehensive protection, consider using robust antivirus software and a reliable VPN service. Check out our recommendations for the best antivirus for Windows and top VPN services.
Other Browser Updates
Alongside Firefox 151.0, Mozilla has released ESR versions 140.11.0 and 115.36.0. The latter supports Windows 7 and 8.1, as well as macOS 10.12 to 10.14. The ESR updates incorporate the same security fixes applicable to those older platforms.
Stay tuned for Firefox 152, expected on June 16, which will bring additional features building on the foundation laid by version 151.