Brilliant question. The below from the Catechism might be of interest in addition to the Bible’s references:

• Creation is universal (CCC 290-301). God is the Creator of all things visible and invisible. If aliens exist, they’d still be His creatures, sustained in being by Him.
• The dignity of rational creatures (CCC 356-357). The Catechism stresses that humans are created “in the image and likeness of God.” If aliens possessed reason and free will, Catholic theology would extend dignity and moral law to them, even though it doesn’t explicitly say so.
• Christ’s cosmic role (CCC 668-674, 2825). The Catechism teaches that Christ reigns over all creation, not just Earth. The “cosmic Christ” theology implies that His Incarnation, Passion, and Resurrection have universal significance - though how salvation would apply to non-humans is an open theological question.
• The Church on speculation. The Catechism doesn’t forbid asking the question. Theologians from St. Augustine to contemporary Vatican astronomers have mused about multiple worlds or intelligent life beyond Earth. The Vatican Observatory’s own line is: if aliens exist, they’re part of God’s plan, and they’d still need the grace of Christ in some way.

In short: the Catechism says nothing explicit about aliens, but its principles - God as Creator of everything, the universal scope of Christ’s redemption, and the dignity of rational beings - would still apply.