I had my vehicle in PARK in my driveway. I was standing outside the vehicle & after I pulled the keys out of the ignition, the vehicle started rolling backward. My feet were on the ground the whole time, the vehicle was in park. I pulled the emergency brake as it was rolling with my legs stuck between the car and the door. I was finally able to push myself into the car to hit the brake with my foot & the car stopped right as it hit the curb of the other side of the street. My legs are extremely bruised from this and if anyone had been behind the vehicle, they would have been ran over as I could not stop it even though it was in park. This just happened so it has not yet been inspected by a mechanic or the dealership. There were no warnings, messages, or symptoms before this happened. It was clearly sitting in park perfectly fine before the engine was turned off. This is extremely dangerous. I have a video from my security camera that shows the entire incident. I'm unable to upload.