Firefox

Is Firefox safe?

Yes. Firefox is a safe browser and one of the most private you can install without changing a single setting. It blocks cross-site cookies and known trackers by default, it encrypts your synced passwords and history so that Mozilla cannot read them, and Mozilla has reported only one Firefox flaw used in real attacks since 2024. The catch is that Mozilla needs money too: sponsored tiles on the New Tab page and usage data sent back to Mozilla are both on until you turn them off. We score it 79/100, well above Google Chrome (59) and a little below Brave (80), which also blocks ads.

What data does Firefox collect?

Less than most browsers. Apple's App Store label lists only your email address and name as linked to you, and only if you create a Mozilla account. Usage data, advertising data and crash reports are collected but not linked to you, and there is no "used to track you" section.

The privacy notice, in force since 4 May 2026, fills in the detail. By default Firefox sends Mozilla "technical and interaction data", such as how many tabs you open and which sponsored tiles you click. A separate daily ping tells Mozilla only that the browser is in use. Both can be switched off. On the New Tab page, Firefox shows sponsored shortcuts and stories, and Mozilla shares data about views and clicks with advertising partners "on an aggregated and/or de-identified basis". In the US, address-bar suggestions, some of them sponsored, are fetched through a relay that hides your IP address from Mozilla.

Mozilla's ad plans are the part to watch. In June 2024 it bought Anonym, a company that measures ad campaigns without sharing individual data. In July 2024 Firefox 128 switched on "Privacy Preserving Attribution", which lets advertisers count ad results through the browser. The privacy group noyb filed a GDPRGDPRThe EU's General Data Protection Regulation, which sets rules on how organisations collect and use personal data and allows large fines.More in the glossary complaint with Austria's data protection authority in September 2024 because users were not asked. We found no decision. Firefox's own source code shows the setting turned off by default from Firefox 143 in September 2025, and Mozilla removed the feature's code in Firefox 155 in 2026.

What changed in the 2025 terms of use?

On Wednesday 26 February 2025 Mozilla introduced new terms of use and a new privacy notice for Firefox. A licence clause in the terms and the removal of the old promise that "we never sell your data" from its FAQ caused an outcry. Two days later Mozilla rewrote the licence and dropped a reference to its Acceptable Use Policy. The new wording says "You give Mozilla the rights necessary to operate Firefox", grants a licence only "for the purpose of doing as you request with the content you input", and gives Mozilla no ownership of that content. The terms in force since 16 September 2026 keep the opening line.

Mozilla did not restore the old promise. It explained that some laws define a "sale" of data so broadly that sharing de-identified ad data could count. The privacy notice still says "What little we do know, we never sell", and it rules out sharing your browsing history, searches or saved passwords with marketing partners. Mozilla says the change was about legal definitions, not new data flows. The wording changed, and so did some users' trust.

How secure is Firefox?

Firefox has a solid record. Mozilla's own advisories report one Firefox bug exploited in the wild in 2024: CVE-2024-9680, a flaw in animation code that ESET found being used with a Windows sandbox escape, fixed in Firefox 131.0.2 on 9 October 2024. In 2025 Mozilla reported none. Its biggest fix that year, CVE-2025-2857 in March, closed a Windows sandbox escape that its own developers found after Google patched a similar bug used in attacks on Chrome. In July 2026 Firefox 152.0.6 fixed two critical bugs with public exploit code but no known attacks.

Firefox Sync is end-to-end encryptedEnd-to-end encryptionEncryption in which only the sender and the recipient can read a message. The company running the service cannot see its content.More in the glossary: your bookmarks, passwords and history are encrypted on your device, and Mozilla says it "cannot decrypt this information". That is stronger than Chrome, where Google holds the keys unless you set a passphrase. Mozilla runs a bug bounty that pays up to $20,000 for critical or high-rated flaws. On iPhone and iPad, Firefox must use Apple's WebKit engine, so its security there depends on Apple's fixes.

Firefox and ad blockers

Firefox still supports the older kind of extension that Chrome switched off in 2025. Mozilla said in March 2024 that it has "no plans to deprecate MV2" and would give at least 12 months' notice of any change, so the full uBlock Origin keeps working. Extensions remain a risk of their own: install only ones you need from addons.mozilla.org and remove those you stop using.

How to make Firefox more private

1. Turn off "Allow Firefox to send technical and interaction data to Mozilla" and the daily usage ping in the privacy settings.
2. Turn off sponsored shortcuts and sponsored stories in the New Tab settings, and sponsored suggestions in the search settings.
3. Switch Enhanced Tracking Protection from Standard to Strict if you can live with a few broken sites.
4. Use the "Block AI enhancements" switch, added in Firefox 148 in February 2026, if you want no AI features at all.
5. Add a Mozilla account only if you want Sync. Without it, Mozilla holds no account data about you.

How we scored it

Privacy (80) and security (80) are both strong: private defaults, encrypted Sync and few exploited bugs. Privacy loses points for telemetry and sponsored content that are on by default, and for ad attribution that Firefox turned on without asking in 2024 and only switched off in 2025. The regulatory record (92) is clean apart from a pending complaint. For a browser that also blocks ads by default, see DuckDuckGo.