How do cruise missiles stay aloft?
Many cruise missiles have wings of some sort, although these can be very small like on the P-700 (barely larger than their control surfaces) or foldable in such a way that makes them not obvious when the missile is in a stowed configuration, like on the Tomahawk or Kh-55.

Additionally, the narrow body of the missile provides lift. Though it is much less effective at it than a wing would be, this is a design trade-off that can be worth it in some scenarios. For supersonic cruise missiles the narrow-body lift is usually enough and the lack of wings is a plus, as they would generate a disproportionate amount of drag at $M_{\infty} \geq 1.0$. 

One of the main traits of slender wings (and bodies) is that their effect on the surrounding airflow grows with speed at a much  slower rate than that of a high-aspect-ratio wings, making them suitable for high speed applications.