Furnace flue PVC pipe joint is dripping water

There's a slow drip at a joint in PVC pipe. I have attached a photo of the flue in the attic. Red arrow shows where the water is dripping from.

Reading up about the problem, I learnt that it could happen in a high efficiency furnace if the joint is no longer intact.

Is there something I can do to seal up the joint without having to take the pipes apart? Is there any product I can apply around the joint to seal the leakage? Any specific procedure to follow?

Thank you very much for any help.