27 Without prejudice to the principles noted earlier, Eastern Christians who are in fact separated in good faith from the Catholic Church, if they ask of their own accord and have the right dispositions, may be admitted to the sacraments of Penance, the Eucharist and the Anointing of the Sick. Further, Catholics may ask for these same sacraments from those non-Catholic ministers whose churches possess valid sacraments, as often as necessity or a genuine spiritual benefit recommends such a course and access to a Catholic priest is physically or morally impossible.
Source: Orientalium Ecclesiarum (Vatican.va)