Roy Hodgson gave the former Newcastle youngster his first England cap in a friendly against Chile in November after Forster impressed in the UEFA Champions League over the past two seasons.
Forster is now aiming to secure his place on the plane to Brazil for the World Cup, where England will face Italy in the group stage.
Buffon is backing the 25-year-old to do well, although the Juventus stalwart acknowledges that Manchester City keeper Joe Hart remains England's number one.
"Joe Hart is fighting for one of the most competitive league championships in Europe and has two very big games in Europe coming up against Barcelona," Buffon told the Daily Record.
"It would be very difficult for the England coach to choose anyone other than Joe as the number one in Brazil.
"But Fraser has to be on the plane, it would be the wrong option not to take him. He is the clear number two.
"Anyone who has seen his performances for Celtic knows what an exceptional talent he is."