To bring a pylon box of an aircraft engine attachment pylon as close as possible to a wing box, two lateral front fasteners are provided. Each of the fasteners comprises a clevis secured to the wing box, the clevis comprising two webs, at least one of which passes through an upper spar of the box, the upper part of one of the two opposite lateral flanges of a lower transverse rib of the box reinforcement, the upper part of an associated lateral panel, and a pin system passing through the clevis and the two upper parts.