A vehicle seat includes a seatback extending from a first side to a second side. An airbag assembly having a housing is supported by the seatback at one of the first and second sides. An airbag is inflatable from the housing to an inflated position. In the inflated position, the airbag has a first leg extending away from the seatback and a second leg spaced from the seatback, and extending from the first leg in a cross-seatback direction to a distal end of the second leg. A panel extends from the distal end of the second leg to the housing.