Pace bowler Kumara, who suffered a left thigh injury in training, is the third Sri Lanka player to be ruled out the tournament, with Chamika Karunaratne replacing Dasun Shanaka and Angelo Mathews coming in for Matheesha Pathirana
Dushmantha Chameera has been added to Sri Lanka's World Cup squad, replacing Lahiru Kumara.
Pace bowler Kumara sustained an injury to his left thigh during a training session in Pune and has been ruled out of the remainder of the tournament.
The 26-year-old featured in two of Sri Lanka's five group matches, returning 0 for 47 against Australia and player of the match-winning figures of 3 for 35 in his side's eight-wicket win over England.
Lahiru Kumara picked up three wickets against England [Gareth Copley/Getty Images]
Injuries have plagued Sri Lanka with Angelo Mathews and Chamika Karunaratne previously brought in as replacement players [Gareth Copley/Robert Cianflone/Getty Images]
Kumara is the third Sri Lanka player to leave the tournament due to injury, with captain Dasun Shanaka (quad) replaced by Chamika Karunaratne and Matheesha Pathirana (shoulder) replaced by Angelo Mathews.
Chameera flew to India as a travelling reserve, alongside Mathews, ahead of Sri Lanka's meeting with Netherlands on October 21.
The 31-year-old, who has taken 50 wickets in 44 ODIs since making his debut in January 2015, was due to be included in the original 15-strong squad but failed to prove his fitness after a series of injuries.
His most recent outing came against Afghanistan in June before being ruled out of the World Cup qualifying event with a torn pectoral muscle and picking up another injury during the Lanka Premier League.
Sri Lanka have won two of their five matches in the tournament to date and currently sit in fifth position, four points outside the top four. They face Afghanistan in Pune on October 30.