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.
Adrian Mutu's move from Cesena to Genoa has fallen through after the Grifoni club pulled out of the transfer.
The Romanian striker was on the verge of completing his transfer to Liguria only for the deal not to materialise, much to the disappointment of Cesena.
Cesena are eager to sell some of their top stars after following their relegation from Serie A last season.
"With regards to Adrian, we had a deal agreed with Genoa," Cesena president Igor Campedelli said to Sky Italia. "However, everything then collapsed.
"Mutu is on the market and we'll see what happens between now and August 31."
Mutu, 33, moved to Cesena from Fiorentina last summer and scored eight goals in 28 league appearances for the Seahorses.
The former Chelsea player has one year left on his contract with Cesena.