The vulnerability resides in modern aircraft’s implementation of CAN (controller Area Network) bus, a popular vehicular networking standard used in automobiles and small aircraft. A hacker with physical access to a small aircraft’s wiring could attach a device or co-opt an existing device to the plane’s avionics CAN bus to insert false data and communicate them to the pilot. The U.S. Department of Homeland Security issued an alert for the same, warning owners of small aircraft to be on guard against a vulnerability.
Source: https://thehackernews.com/2019/07/airplane-can-bus-hacking.html