You can drive a car with an exhaust leak however you really shouldn't drive the car with an exhaust leak especially if the exhaust leak is under the car because if the exhaust is leaking under the car it can get into the cars interior and cause carbon monoxide poisoning.
If the exhaust is leaking through the exhaust manifolds then it's less dangerous but still dangerous to your health anyway and can decrease fuel mileage and cause a loss of engine power.
If the leak is under the car you should drive it to the nearest muffler or exhaust shop and have a new exhaust system put on the car soon or put a new exhaust system on yourself or get the leak fixed because you or someone else in the car could get sick really bad or even potentially die.