I would not be surprised that most USB devices will actually survive that without any damage. It's usually not possible to use USB's roughly 5V directly (becaus

I would not be surprised that most USB devices will actually survive that without any damage. It's usually not possible to use USB's roughly 5V directly (because it's not actually reasonably exact 5V and modern logic often uses lower voltages) and thus most devices contain some kind of switchmode power supply (linear regulators essentially cannot be used due to strict input current requirements of USB specification) that tends to be designed to work up to input voltages of tens of volts.