The 28-year-old Northern Ireland international striker looked set to complete a switch to Elland Road last week until the injury apparently rose to prominence during his medical.
Feeney is unlikely to get many first-team minutes under his belt with City this season due to competition for places in attack, and whether his switch to Leeds will be back on following his return to full fitness remains to be seen.
Bluebirds chief Peter Ridsdale told the South Wales Echo: "Medical staff tell us it's exactly the same problem Roger Johnson had last season. Warren is back with us and will have surgery to sort out his hip. He'll be back to 100% in a short time."
Meanwhile, Cardiff have linked up with Spanish giants Valencia in a bid to help enhance coaching techniques and player development across both club's various age groups.