Google fixed previously unknown flaws in Android that allowed authorities to unlock phones using forensic tools.
Researchers from Amnesty International found a chain of three zero-day vulnerabilities in the core Linux USB kernel.
The vulnerabilities, developed by Cellebrite, impacted over a billion Android devices.
Amnesty International and Google's anti-hacking unit, Threat Analysis Group, collaborated to fix the vulnerabilities after investigating a student protester's hacked phone.