Youcat commented through CCC – Question n. 238.

YOUCAT Question n. 238 - May a priest later repeat something he has learned in confession?

(Youcat answer) No. Under no circumstances. The secrecy of the confessional is absolute. Any priest who would tell another person something he had learned in the confessional would be excommunicated. Even to the police, the priest cannot say or suggest anything.

A deepening through CCC

(CCC 2490) The secret of the sacrament of reconciliation is sacred, and cannot be violated under any pretext. "The sacramental seal is inviolable; therefore, it is a crime for a confessor in any way to betray a penitent by word or in any other manner or for any reason" (CIC, Can. 983 § 1).

Reflecting and meditating 

(Youcat comment) There is hardly anything that priests take more seriously than the seal of the confessional. There are priests who have suffered torture for it and have gone to their deaths. Therefore, you can speak candidly and unreservedly to a priest and confide in him with great peace of mind, because his only job at that moment is to be entirely “the ear of God”.

(CCC Comment)

(CCC 1467) Given the delicacy and greatness of this ministry and the respect due to persons, the Church declares that every priest who hears confessions is bound under very severe penalties to keep absolute secrecy regarding the sins that his penitents have confessed to him. He can make no use of knowledge that confession gives him about penitents' lives (Cf. CIC, can. 1388 § 1; CCEO, can. 1456). This secret, which admits of no exceptions, is called the "sacramental seal," because what the penitent has made known to the priest remains "sealed" by the sacrament.

(The next question is:  What are the positive effects of confession?)