AliExpress caught fingerprinting shoppers with inaudible audio, and it hijacked a dev's Bluetooth headphones
Leave an AliExpress tab open and the site quietly fingerprints you: heavily obfuscated scripts fire sawtooth waves through the Web Audio API to turn your own hardware into a unique device signature. Developer Matt Callaghan only noticed because the inaudible tones kept stealing his Bluetooth headphones from his phone. Firefox and Brave say they already block the trick. Silent tracking, it turns out, still leaks.