Browser Math Reveals OS Fingerprint, Threatening Anti‑Bot Defenses
Cosine‑like functions such as Math.tanh produce OS‑specific rounding errors because browsers delegate to the host libm. This tiny variance creates a reliable fingerprint that anti‑bot systems can read, exposing the underlying OS even when User‑Agent strings are spoofed. The leak appeared with Chrome 148 after V8 switched to the system library.