They're part of what's known as the "deuterocanonical" books - they're in practice the same as what Protestants refer to as the "Apocrypha" but accepted by us as canonical. The introduction to I Maccabees in the New American Bible (which is the standard American Catholic translation) says: "The Books of Maccabees, though regarded by Jews and Protestants as apocryphal, i.e., not inspired Scripture, because not contained in the Palestinian Canon or list of books drawn up at the end of the first century A.D., have nevertheless always been accepted by the Catholic Church as inspired, on the basis of apostolic tradition."

Here is the US Conference of Catholic Bishops online Bible (the NAB translation). All the books included are considered canonical.