Is the Catholic Church the only path to salvation?
No. From the Catechism of the Catholic Church:
819 "Furthermore, many elements of sanctification and of truth" are found outside the visible confines of the Catholic Church: "the written Word of God; the life of grace; faith, hope, and charity, with the other interior gifts of the Holy Spirit, as well as visible elements." Christ's Spirit uses these Churches and ecclesial communities as means of salvation, whose power derives from the fullness of grace and truth that Christ has entrusted to the Catholic Church. All these blessings come from Christ and lead to him, and are in themselves calls to "Catholic unity."