The England goalkeeper, 27, required surgery on a knee injury sustained in an awkward fall during the 2-0 home win over Burnley on March 21 and estimates over his recovery period have ranged from four months to a year.
Korman said: “If you say it’s four months, it’s seven months and after seven months you will get the answers about the situation with Fraser.
“At least this season [he will be out] and then we will see for the next season. Fraser is down, of course. I spoke to him last week.
“The operation he had last week went okay, but he will be out for a long time – at least for this season. We have to wait to see how long he will be out for, it’s difficult at this moment.
“Fraser is a fantastic goalkeeper. He was and is the number one for us. But as for every player you need good substitutes for each position.
“Kelvin Davis is a very experienced goalkeeper who played very well against Burnley. He made some fantastic saves and has a lot of experience, which is important for our last eight games of the season.
“We have to make a decision on the goalkeepers at the end of the season and if Fraser is out for a longer time, a new goalkeeper is an option.”
“I have also had to respond to a lot of the questions about [injured striker] Jay Rodriguez. Jay has been training with the group and should be ready to play in four or five weeks.”
Davis will once again be between the sticks when Southampton continue their push for Champions League football at Everton on Saturday.