The contact owns a 2018 Ford F-150. The contact stated that while driving at an undisclosed speed, the brake fluid warning light illuminated. The contact pulled over to the side of the road, added brake fluid, and continued driving. The contact stated that upon depressing the brake pedal, the brake pedal went down to the floorboard, and the vehicle failed to respond as needed. The contact pulled over to the side of the road and added brake fluid to the vehicle; however, the failure persisted. The contact was able to drive to an independent mechanic, where it was diagnosed that the brake master cylinder had failed and needed to be replaced. The vehicle was not repaired. The contact related the failure to NHTSA Campaign Number: 25V236000 (Service Brakes, Hydraulic); however, the VIN was not included. An unknown dealer was notified of the failure. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 75,000.