Firefox 151: Enhanced Privacy, PDF Merging, and Critical Security Patches
Welcome to the latest major update from Mozilla. Firefox 151 delivers a host of privacy enhancements, new features for the built-in PDF tool, and crucial security fixes for over 30 vulnerabilities. Whether you’re a privacy enthusiast or a casual user, this version brings meaningful improvements. Below, we break down the most important changes in a Q&A format.
What new VPN features are available in Firefox 151?
Firefox’s free VPN service, first introduced in version 149, now lets you choose from multiple virtual locations. Users in the US, Canada, the UK, France, and Germany can select their own country as a VPN endpoint. To use the VPN, you’ll need a free Mozilla account, and you’ll get 50 GB of traffic per month. This location selection feature is being rolled out gradually, so if you don’t see it yet, check back soon. It’s a significant step toward giving you more control over your online privacy.
How does the one-click private session clearing work?
If you rely on Firefox’s private windows, you’ll love this update: you can now clear an entire private session with a single button click. No need to close the browser window or manually delete history. Just click the button, and a fresh private session starts instantly with no trace of your previous activity. This makes it easier than ever to compartmentalize your browsing without any hassle.
What improvements were made to tracking protection?
Mozilla has enhanced Firefox’s tracking protection in version 151. According to the company, these updates can reduce the number of users that advertisers can identify via standard fingerprinting techniques by 14% overall. On macOS, the reduction is even more dramatic—up to 50%. This means your browsing habits will be harder to track, giving you a stronger shield against invasive advertising and data collection.
What’s new on the New Tab page?
The redesigned New Tab page now offers a wider selection of background images. Mozilla has also prepared the page for upcoming features that will launch in the lead-up to Firefox 152, scheduled for June 16th. While the current changes are subtle, they set the stage for more interactive and personalized content. Expect more enhancements in the next release.
Can I now merge PDFs in Firefox’s built-in viewer?
Yes! Firefox 151 adds the ability to merge multiple PDF files into a single document directly in the built-in PDF viewer/editor. This is a handy feature for anyone who frequently works with PDFs and wants to combine reports, forms, or research papers without needing third-party software. Simply open the PDF tool, select the merge option, and arrange your files.
What other usability improvements are included?
Two smaller but welcome updates: First, the internal page for translating text (accessible at about:translations) is now available from the menu under “More Tools.” This saves you from typing the address manually. Second, Linux users can now back up their Firefox profiles locally and restore them across different platforms. This makes switching devices or recovering lost data much simpler.
How many security flaws were fixed in Firefox 151?
Mozilla’s Security Advisory 2026-46 lists over 30 fixed vulnerabilities. Of these, 28 were reported by external researchers. Four are classified as high risk, including a potential browser sandbox escape (CVE-2026-8945). Eleven are medium risk, and the rest are low risk. The advisory also notes three internally discovered memory management bugs. Keeping your browser updated is vital, so consider pairing it with robust antivirus software for complete protection.
Are there updates for Firefox ESR versions?
Yes, alongside Firefox 151.0, Mozilla released ESR versions 140.11.0 and 115.36.0. The latter is only available for legacy operating systems: Windows 7/8.1 and macOS 10.12 to 10.14. These ESR updates include fixes for the vulnerabilities present in those codebases, ensuring that users on older systems still receive critical security patches.