"And he cast down the pieces of silver in the temple, and departed, and went and hanged himself" (Matthew 27:5)
"Now this man purchased a field with the reward of iniquity; and falling headlong, he burst asunder in the midst, and all his bowels gushed out" (Acts 1:18).
Ancient terminology did not recognize “hanging” just as hanging from a rope, but as hanging on anything. For instance, it is said accurately that Jesus was “hung” on a tree, even though he was nailed there. I believe Judas hung himself not with a rope around his neck, but by impaling himself on a pike causing his intestines to spill-out which in ancient terminology would have been referred to as “Judas hanging himself.” The bible isn't specific, but it says Judas fell headlong, not as a person falling feet-first from a rope. So its likely he secured a spear into the ground, piled up some stones, and jumped/fell headfirst, thus making Matthew and Acts correct.