Catechism of the Catholic Church §2454 — excerpt
Every manner of taking and using another's property unjustly is contrary to the seventh commandment. the injustice committed requires reparation. Commutative justice requires the restitution of stolen goods.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.