The Leinster centre picked up the injury in the Heineken Cup final win over Northampton Saints. He had to go under the knife after the problem failed to respond to conventional treatment.
Ferris has been a long-term absentee due to ligament damage in his left knee. He has not played competitively since sustaining the injury during Ulster's Heineken Cup win over Aironi last January.
He has since had his knee operated on and is hoping to give the Ireland management 'a selection headache' as he edges closer to his return in the green jersey.
Speaking before today's training session at Carton House, Ireland team manager Paul McNaughton said: "Gordon is tight to make the World Cup. He recovers quickly and is running while bearing his full weight, so is making progress.
"With these type of injuries, a week can tell us a lot - players can progress a lot in that time as well.
"Gordon and Stephen face a race against time but are making progress. If there is a likelihood of guys not playing before the World Cup then it's those two.
"We're hopeful that they may be ready for game-time, maybe in match three or four of the summer series."
Ireland will start their run of warm-up games before the World Cup against Scotland at Murrayfield next Saturday afternoon.
Then they face back-to-back Tests against France before wrapping the month up against England at the Aviva Stadium on Saturday, August 27.
A friendly match against a Connacht selection has also been throw into the mix at Donnybrook on Thursday, August 18.
"It's a preference that they have some game-time before they go, but we'll never say never on anybody. A player could be just a week away from full fitness but it would be dangerous to play him in a game," explained McNaughton.
Ireland captain Brian O'Driscoll has a shoulder/neck injury at the moment and is unlikely to play in either of Ireland's away games this month against Scotland (August 6) and France (August 13).
"Brian has been doing 80% of the work over the last two weeks. I'm not too concerned about him.
"He has a problem with his shoulder/neck and has been having some traction on it. He's doing everything except contact this week."
McNaughton said that injuries have cleared up for some of the squad's long-term concerns - namely Rob Kearney (knee), Jerry Flannery (calf) and Geordan Murphy (foot/ankle).
The plan of action for the majority of the 43-man training squad is to play 'two-and-a-half to three games' over the next month, with players also being given game-time in the provinces' pre-season friendlies if necessary.
Leinster flanker Shane Jennings is resuming contact work this week. He spent a number of weeks on the sidelines after having surgery on a broken arm.
With the Ireland team to face Scotland announced on Thursday afternoon, it seems that Kearney, Flannery and Murphy are all in contention.
Both Kearney and Murphy played in last November's Tests, but the injury-plagued Flannery has been absent from the international scene since the 2010 RBS 6 Nations.
"Flannery, Kearney and Murphy are ready to go. They were involved in contact last week and are ready for game-time," confirmed McNaughton.
"Flannery has been out for quite a while now (since January). He has been getting specialist rehab on a one-to-one basis during the summer.
"But over the last two weeks he has kept up fully in training. We're pleased to see him take part in everything from contact to scrummaging.
"In general, the injury situation has been getting better over the last couple of weeks, but we have five matches and need to give guys game-time. We're hopeful that every player will partake in some games."