A screw will be placed in McCargo's foot to help the fracture heal faster.
McCargo, the second of Buffalo's two first-round draft picks, was hurt late in the fourth quarter of Sunday's game.
The Bills traded up on draft day to grab the North Carolina State product, who manned a collegiate defensive line that included fellow draftees Mario Williams and Manny Lawson.
McCargo has six tackles in five games this season. He had two tackles on Sunday.