The catechism is infallible insofar as it is interpreted by the Pope in whatever form he chooses to do that. Once the Pope interprets the catechism (or re-interprets it), it is infallible. That said, the catechism of the church has indeed changed, most notably during the Counter-Reformation .

Is Catholic catechism infallible?

While the catechism contains the infallible doctrines proclaimed by popes and ecumenical councils in church history — called dogmas — it also presents teachings not communicated and defined in those terms. In other words, all dogmas are considered doctrines, but not all doctrines are dogmas.

Is the catechism binding?

A dogma of the Catholic Church is defined as "a truth revealed by God, which the magisterium of the Church declared as binding." The Catechism of the Catholic Church states: ... The faithful are only required to accept those teachings as dogma if the Church clearly and specifically identifies them as infallible dogmas.