Mozilla studied 25 million Firefox users to defeat cookie-less tracking
Open research, stronger privacy: Making Firefox users harder to fingerprint
Mozilla analyzed browser fingerprinting data from nearly 25 million Firefox users to find which details — screen size, processor count, fonts — make people uniquely identifiable. Protecting just a handful of features sharply weakens popular fingerprinting techniques from Fingerprint Pro, Signifyd, and Akamai. The resulting protections, newest in Firefox 145, shrink the number of users with unique fingerprints and enlarge the groups that share one. The work is published openly and accepted at CCS 2026.
Our goal is to make more users' browsers look similar to fingerprinting scripts while preserving the information websites need to function correctly, like language and timezone settings.
- MayeulC
I feel like I am commenting this under every post mentioning fingerprinting, but is there a technical reason access to fingerprinting information (screen resolution, battery level, etc) couldn't be made to "taint" the data/code, where the browser would then refuse to send off that data? Or anonymise it and replay the code before sending the request.
Of course, there are legitimate use-cases: downloading specific assets based on client device, etc. And that's a whole can of worms of side channels to open, but that would feel like a useful additional layer of defense, and the paranoia level could be configured. The price might be subtle bugs, and/or a permission dialog that most people will ignore.
I am asking this as, from what I've seen, most websites do not need complex interactions: the battery level will be used to render a battery indicator, etc. XHRs do not usually depend on such data.
- ada-h00k
I think it's great that Firefox is finally doing more to combat fingerprinting. For a long time, they lagged a bit behind Brave in this regard. That said, unfortunately, neither browser has been able to do anything about Cloudflare Turnstile yet. Kagi, for example, uses it to fingerprint users.
- asciimoo
Too bad they still generate a random unique ID for each installed extension that can expose a trackable UUID...
- theyeenzbeanz
One caveat I’ve experienced with Firefox branches that focus on privacy is I get “punished” with captchas from hell because I refuse to let websites siphon and prey on every last bit of private info. Hopefully this doesn’t succumb to the same issue.
- idbehold
I'd like to have some of the APIs that read the data used to fingerprint browsers be behind a confirmation dialog per site similar to allowing popups or microphone/video access.
> Oh, I see that you'd like to read the canvas pixel data, let me check if that's okay with the user first.