Meta devised an ingenious system (“localhost tracking”) that bypassed Android’s sandbox protections to identify you while browsing on your mobile phone — even if you used a VPN, the browser’s incognito mode, and refused or deleted cookies in every session.
This is the process through which Meta (Facebook/Instagram) managed to link what you do in your browser (for example, visiting a news site or an online store) with your real identity (your Facebook or Instagram account), even if you never logged into your account through the browser or anything like that.
Meta accomplishes this through two invisible channels that exchange information:
(i) The Facebook or Instagram app running in the background on your phone, even when you’re not using it.
(ii) Meta’s tracking scripts (the now-pulled illegal brainchild uncovered last week), which operate inside your mobile web browser.
Since January Google has been using browser fingerprinting and IP triangulation to track across incognito windows.
Meta wants in the game as well. Nothing done on a phone with Meta apps is done in isolation.
Edit: seems like only vanilla mobile browsers affected. Brave was not vulnerable, DDG minimally so, and I expect Iron/Waterfox with uBlock would also not have allowed tracking.
https://securityonline.info/androids-secret-tracking-meta-yandex-abused-localhost-for-user-data/
