Catechism of the Catholic Church

Respect for the reputation of persons forbids every attitude and word likely to cause them unjust injury. He becomes guilty: - of rash judgment who, even tacitly, assumes as true, without sufficient foundation, the moral fault of a neighbor; - of detraction who, without objectively valid reason, discloses another's faults and failings to persons who did not know them; - of calumny who, by remarks contrary to the truth, harms the reputation of others and gives occasion for false judgments concerning them.