KRACK Attack Broke WPA2 by Reusing Encryption Keys

In 2017, researcher Mathy Vanhoef revealed KRACK, an attack that exploited a flaw in the WPA2 four-way handshake to force key reinstallation and nonce reuse. This allowed attackers within Wi-Fi range to decrypt traffic, with Linux and Android 6.0+ devices particularly vulnerable due to an all-zero key installation. The attack did not crack passwords but targeted the protocol itself, affecting virtually all WPA2 networks.