The magicians at KrackAttacks demonstrated a successful attack on WPA2 protocol, which powers most Wi-Fi networks today. A flaw makes it possible for attackers to eavesdrop on your data when you connect to Wi-Fi. Dubbed KRACK, the issue affects the Wi-Fi protocol itself, not specific products or implementations, and "works against all modern protected Wi-Fi networks," according to the researchers that discovered it. That means that if your device uses Wi-Fi, KRACK likely impacts it.

Due to how heavy this issue is, the researches made a whole website dedicated to it here, explaining what it is, how it works, which systems it affects and how to protect yourself against it. I specifically recommend this read to all Android and Linux users (at least the Q&A part, since it's less technical), which are still waiting for a proper patch for their systems, but also to everyone else who use outdated systems or systems with auto-updating disabled.