I will disagree with the other commenter and say that this is more plausible for the aircraft than for the cars. Modern jetliners and military aircraft (scarrier yet) are purely fly-by-wire - there aren't cables running between the yokes and the control surfaces like in a Piper Cub, and if there were, no pilot would be strong enough to move them.

Yes, the autopilots can be turned off, but that's just a button, probably a button on the autopilot itself. Depending where the infection happens, the actual position of the yoke could be entirely ignored by the software. Or the motor controllers for the control surfaces themselves could be driving the plane, though I don't know how they could coordinate their actions and get feedback from an IMU.

Perhaps the pilots could rip out components and cut cables fast enough to prevent the plane from reaching its destination, and maybe they could tear out the affected component and limp back to a runway with what remains, but it's an entirely feasible movie plot.

But should we actually worry about either? No. The software sourcing, deployment and updating protocols at the various manufacturers of aircraft are certain to be secure. Right?