Security researchers have discovered several severe zero-day vulnerabilities in mobile bootloaders from at least four popular device manufacturers. The vulnerabilities impact the “Trusted Boot” or Android’s “Verified Boot” mechanisms that chip-set vendors have implemented to establish a Chain of Trust (CoT), which verifies the integrity of each component the system loads while booting the device. Some of the flaws even allow an attacker with root privileges on the Android operating system to execute malicious code as part of the bootloader or to perform permanent denial-of-service attacks.
Source: https://thehackernews.com/2017/09/hacking-android-bootloader-unlock.html