What causes my brake lights to remain on after the engine is turned off? on 2002 Hyundai Santa Fe

My brake lights remain on when the engine is turned off and is draining the battery. Could this be the brake master cylinder, if so, what is estimate of cost to repair?

Asked by for the 2002 Hyundai Santa Fe
It won't be the brake master cylinder it is more likely a failed brake light switch about .5 hour to replace.