Do you have a moonroof?

When I had the same problem, it turned out that the water drain that drains from the moonroof track / channel had gotten clogged up and instead of dumping water somewhere behind the wheel, it leaked it into the car.

It was under warranty at the time so I had them fix it.

It happens in other cars as well, as I remember having to take my mom's Acura Legend into the dealer for the same thing once. Good luck!