Cardiff will allow long-serving Kevin McNaughton to leave this summer along with Danny Gabbidon and Nicky Maynard.
Highly-rated Atletico Madrid midfielder Saul Niguez has signed a new five-year contract.
St Mirren boss Danny Lennon has put talks with his out-of-contract players on hold while he focuses on keeping the Buddies in the SPL.
Goalkeeper Craig Samson revealed this week he has turned down a take it or leave it offer from the Paisley outfit, while deals for his team-mates Paul McGowan, Graham Carey and Sam Parkin also expire in the summer.
But Lennon says he has put those matters to one side while he places his full attention on holding off a resurgent Dundee side.
The Dens Park club's 2-1 win at St Mirren Park last weekend reduced the gap separating them and the Buddies at the bottom of the SPL to just 10 points with 12 to play for.
A win over Hibernian at Easter Road on Saturday, however, will guarantee safety for Saints while sending the Dark Blues back to the Irn-Bru First Division and that is all Lennon is thinking about.
He told Press Association Sport: "I've put all contractual stuff on hold this week just so I can get back to concentrating on what we need to do, which is pick up points.
"Dundee are fighting for their lives and John (Brown) has come in and done a terrific job. They have nothing to lose now and are just going for it game after game.
"But we can't concentrate on them, we can only influence what we do ourselves. It's in our hands and we will be going out in each of these last four games for a victory."
Lennon says he "respects" Samson's decision to decline the offer of a new deal but he has not given up all hope of retaining the services of Portuguese striker Esamel Goncalves.
The on-loan Rio Ave frontman - who returns for the Leith trip after serving a two-match ban for diving against Celtic last month - has earned himself iconic status amongst the Paisley faithful after grabbing one of the goals in the
Buddies' 3-2 Scottish Communities League Cup final success over Hearts.
His parent club have already announced they expect to see the player back in Portugal at the end of the season and may look to sell him on for a profit.
St Mirren simply do not have the budget to make a bid themselves but Lennon hopes the potential to further develop a player who has scored six goals in 11 outings for Saints may persuade Rio Ave to send him back for a second loan stint.
"It's great to have Esma back for Saturday's match," said Lennon.
"He's been a big player for us and made a big impact since his arrival on loan from Rio Ave.
"He's a lovely lad who just loves to get out there and play football. His move has worked well for all three parties. It's been a pleasure working with him and I'm hoping in the four remaining games we see his true potential coming out again.
"He will return to Portugal in the summer but I wouldn't rule it out him coming back here again. Our ambition is to keep him but I respect Rio Ave's decision.
"I know he's loved his time here and he has developed with us. I think he'd like to develop further here but those are questions I can't answer.
"We are never going to have the money to buy a player like that but we can offer a platform to improve players and a window of opportunity."