Forster damaged the patellar tendon in his left knee in the 2-0 Premier League win over Burnley on March 21 and was ruled out for the rest of the season four days later after undergoing surgery.
The England goalkeeper's recovery time could be nine to 12 months, leading Southampton to be linked with shot-stoppers such as Reading's Adam Federici.
And, while manager Ronald Koeman dismissed that rumour, he said: "Of course we've thought about it because maybe we need a goalkeeper.
"He's [Forster] back in the training centre. That's the first step for the player. He's back, he has contact with the players, he's involved in what we're doing in the training centre."
Southampton are eight points behind fourth-placed Manchester City in seventh going into Saturday's meeting with Hull City.
Koeman accepts that the south-coast club's UEFA Champions League challenge is over, and is focused on securing Europa League football.
"You have to be realistic," he added. "It's a lot [the gap], our focus at the moment has to be about the fifth, sixth and seventh positions in the table.
"We like to play European football. We fight for that."
