This problem is being called “unpatchable.” I hope that’s wrong.
Your use of the USB drive is completely dependent on the microcontroller in the USB drive. You have to accept that it's doing what you want -- you can't "patch" anything to avoid it doing its thing, good or bad. At least, you can only try to block the bad behavior you can anticipate. The Bad Guys are always one step ahead.
The only way to totally avoid the problem is to avoid using USB drives. Otherwise it's endless cat-and-mouse.
It's a problem, but so far it hasn't been a prevalent problem because it's rather difficult to exploit. However, the Bad Guys are highly motivated.
If it is in the firmware, that would probably necessitate a redesign...