Cyclones coach Paul Rhoads says Dunning ruptured his patella tendon and Harris broke his leg during Saturday's 20-17 win at Iowa.
Dunning is a backup at left tackle. Harris had nine catches for 55 yards through three games. Dunning and Harris join linebacker Levi Peters, center Ben Loth and standout wide receiver Quenton Bundrage as Cyclones who are expected to miss the rest of 2014.
Iowa State has a bye before hosting No. 7 Baylor on Sept. 27.