The Catechism itself is simply a compendium and summary of the teachings of the Church. the Catechism contains infallible teachings but it not an infallible document. It is not really a level of authority in and of itself, the only authority is from the proclamations of the actual teachings themselves.
As (then) Cardinal Ratzinger noted in his book Introduction to the Catechism of the Catholic Church (p. 27):
The individual doctrine which the Catechism presents receive no other weight than that which they already possess. The weight of the Catechism itself lies in the whole.
And from the USCCB:
Is the doctrinal authority of the Catechism equal to that of the dogmatic definitions of a pope or ecumenical council?
By its very nature, a catechism presents the fundamental truths of the faith which have already been communicated and defined. Because the Catechism presents Catholic doctrine in a complete yet summary way, it naturally contains the infallible doctrinal definitions of the popes and ecumenical councils in the history of the Church. It also presents teaching which has not been communicated and defined in these most solemn forms. This does not mean that such teaching can be disregarded or ignored. Quite to the contrary, the Catechism presents Catholic doctrine as an organic whole and as it is related to Christ who is the center. A major catechism, such as the Catechism of the Catholic Church, presents a compendium of Church teachings and has the advantage of demonstrating the harmony that exists among those teachings.