Jackson suffered the injury to his right leg during workouts on Tuesday, the Eagles said on their website (http://www.philadelphiaeagles.com).
A former first-round draft pick, Jackson was acquired by the Eagles during the off-season after spending five years with the Indianapolis Colts. He started at both safety and cornerback for the Colts.
(Reporting by Gene Cherry in Raleigh, North Carolina. Editing by Steve Ginsburg)