There are 2 cornerbacks, along with a deep middle safety (free safety).
The 33 stack defense has 3 down defensive linemen, 2 defensive tackles and a nose guard.  There are 5 linebackers; 1 inside linebacker lined up stacked over the center, 2 middle linebackers stacked over the defensive tackles, and two outside linebackers. There are 2 cornerbacks, along with a deep middle safety (free safety). This is strictly a gap control defense.