Upvote:4
Documents of ecumenical councils receive their authority from the Pope who solemnly approves them. Councils give council to a Pope, and it is by his authority alone that their documents can be infallible.
Conciliarism, which teaches that a general council of the Church has higher authority than the Pope, is a condemned heresy. The First Vatican Council's infallible document Dei Filius, ratified by Pope Pius IX, stated:
…they err from the right course who assert that it is lawful to appeal from the judgments of the Roman Pontiffs to an œcumenical Council, as to an authority higher than that of the Roman Pontiff.
These conditions follow from the section of Dei Filius regarding papal infallibility:
…we teach and define that it is a dogma divinely revealed: that the Roman Pontiff, when he speaks ex cathedra, that is, when in discharge of the office of pastor and doctor of all Christians, by virtue of his supreme Apostolic authority, he defines a doctrine regarding faith or morals to be held by the universal Church, by the divine assistance promised to him in blessed Peter, is possessed of that infallibility with which the divine Redeemer willed that his Church should be endowed for defining doctrine regarding faith or morals; and that therefore such definitions of the Roman Pontiff are irreformable of themselves, and not from the consent of the Church.
The four conditions are indeed satisfied in Cantate Domino (1442) since Pope Eugune IV
Cantate Domino is thus part of the Extraordinary Magisterium, which Fr. Hardon, SJ, defines as:
The Church's teaching office exercised in a solemn way, as in formal declarations of the Pope or of ecumenical councils of bishops approved by the Pope. When the extraordinary magisterium takes the form of papal definitions or conciliar decisions binding on the consciences of all the faithful in matters of faith and morals, it is infallible.
(cf. my answer here)