The Catechism in Questions & Answers

425. By what authority do the bearers of the Apostle ministry act?

The Apostles are ambassadors of Jesus Christ. They act in His name. He gave the Apostles the authority to fulfil the tasks arising from His ministries, namely King, Priest, and Prophet. They are to exercise the rule of Christ, dispense divine blessing, and proclaim the gospel of Christ.
The authority conferred upon the Apostle ministry comes exclusively from Jesus Christ. The Apostle ministry exists in a relationship of complete dependency on Him.