The Catholic Church does not teach that scripture is sufficient

It is common to hear that the Catholic Church does not teach that scripture is sufficient. But the Church actually teaches that scripture contains or implies all that is needed for salvation.

Dei Verbum Chp 3 “Therefore, since everything asserted by the inspired authors or sacred writers must be held to be asserted by the Holy Spirit, it follows that the books of Scripture must be acknowledged as teaching solidly, faithfully and without error that truth which God wanted put into sacred writings for the SAKE OF SALVATION.”

The Catholic Church teaches that God’s Word was handed down in two modes, written and orally, and both modes work in unison to give us a complete and full understanding of God’s Word. The proper interpretation of scripture is further explained in Dei Verbum 12.

76 In keeping with the Lord's command, the Gospel was handed on in two ways: - orally "by the apostles who handed on, by the spoken word of their preaching, by the example they gave, by the institutions they established, what they themselves had received - whether from the lips of Christ, from his way of life and his works, or whether they had learned it at the prompting of the Holy Spirit"; - in writing "by those apostles and other men associated with the apostles who, under the inspiration of the same Holy Spirit, committed the message of salvation to writing".

Dei Verbum, 12. Holy Scripture must be read and interpreted in the sacred spirit in which it was written, no less serious attention must be given to the content and unity of the whole of Scripture if the meaning of the sacred texts is to be correctly worked out. The living tradition of the whole Church must be taken into account along with the harmony which exists between elements of the faith. It is the task of exegetes to work according to these rules toward a better understanding and explanation of the meaning of Sacred Scripture, so that through preparatory study the judgment of the Church may mature. For all of what has been said about the way of interpreting Scripture is subject finally to the judgment of the Church, which carries out the divine commission and ministry of guarding and interpreting the word of God.