A recently discovered vulnerability could allow attackers to intercept sensitive data being transmitted between a Wi-Fi access point and a computer or mobile device, even if that data is encrypted. The flaw, known as KRACK, affects WPA2, a security protocol widely used in most modern Wi-Fi devices. In some cases, a hacker could exploit KRACK to inject malware such as ransomware into websites, according to KU Leuven's Mathy Vanhoef, the researcher who discovered the vulnerability. Vanhoef's findings were reported by tech site Ars Technica early Monday morning. Here's an overview of what to know about the vulnerability, and how you can protect your devices.