"I tore my quad during the season," Foran said. "My back's been pretty stuffed too. I'm busted.
"I saw the Canterbury medical staff last week and we're getting scans to work out the best treatment and best way forward.
"Medically I can't play in the World Cup. I played under strength for much of the year at the Warriors and I just wasn't strong enough for NRL football. I've got to get my body right.
"I really need a big off-season."
The Kiwis have other options in the No6 jersey, including veteran Thomas Leuluai, Cowboys stand off Te Maire Martin and Broncos utility Kodi Nikorima.
All three are capable of performing a role, though they don't compare to Foran at his best.
But the former Manly and Parramatta player had an inconsistent season with the Warriors in 2017, and may have also struggled with the intensity of the five week tournament.
The Kiwis have also got used to life without Foran.
After being a critical part of the Kiwis' memorable three-peat over the Kangaroos in 2014-15, Foran didn't pull on the black and white jersey for almost two years for various physical, mental and emotional reasons, before coming back into the fold for the Anzac test in Canberra in May.