The 32-year-old will miss the tournament for a second time after fracturing a metatarsal in his right foot, which will keep him sidelined for "three to four months"
According to a short statement released by the team, Saborio will be sidelined for "three to four months."
The 32-year-old is his country's active leading goalscorer and most-capped active player, and his absence will come as a blow to Costa Rica's hopes of escaping the intensely difficult Group D - featuring England, Uruguay and Italy - after a World Cup qualifying campaign that saw him score eight goals.
Saborio had been in hot form this season, scoring six goals and providing two assists in 10 games to help Real Salt Lake to an as-of-yet undefeated start in MLS.
In his absence, Costa Rica head coach Jorge Luis Pinto will likely look to the services of a pair of forwards who spent the 2013-14 season on loan: captain Brian Ruiz of PSV Eindhoven - via Fulham - and youngster Joel Campbell, who spent the campaign farmed out by Arsenal to Olympiacos.