Researchers have discovered a key flaw in the WPA2 Wi-Fi encryption protocol that allows hackers to intercept credit card numbers, passwords, photos and other sensitive information. The new exploit is called KRACK, short for Key Reinstallation Attacks. The research has been kept under wraps for weeks ahead of a coordinated disclosure. The vulnerability affects the core WPA2 protocol itself and is effective against devices running Android, Linux, and OpenBSD, and to a lesser extent macOS and Windows, as well as MediaTek Linksys.