It seems that since Pius X Society are not in communion with the Holy See, their priests should not be able to confess catholics’ that are attending masses there.
Whether a priest has faculties or not is a canonical matter. Pope Francis by virtue of his office possesses supreme, full, immediate, and universal ordinary power in the Church, which he is always able to exercise freely (canon 331).
The Church grants faculties to priests who are not in active ministry already in canon law. Anyone who has been validly ordained a priest has the faculty to hear a confession of someone who is in danger of death (canon 986 §1). This is true even if the priest has no faculties from a bishop, has been suspended or even excommunicated.
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