Or can someone who has been blessed by a priest do so? What if someone were stranded on an island and unable to hear confession?
Can Only A Priest Give Confession?
What I think you mean is whether only a priest can give absolutions for confessed sins? The short answer is yes.
There could be situations of doubt in certain situations though.
I remember reading about the atrocities committed during the French Revolution.
As it happened one day, that one of the revolutionaries was grievously wounded and knew he was dying. Three elderly woman were at his side and seeing that he desired to have a priest present, he asked that two of them go a search out a priest.
The oldest woman remained at his side. He then confessed his sins to the old woman, in the case he went unconscious before a priest arrived to hear his confession.
As it turned out, he went unconscious by the time the pastor of the local church arrived. Having been told of the sins committed by the elderly woman by this revolutionary decided to absolving him conditionally, leaving it to God if the confession was valid or not.
In the history of the Church, there are many strange situations that have happened.
Of course in the absence of a possible confession Catholics are taught to make a perfect act of contrition.