IndiGo flight 6E9371, an Airbus A320neo, was descending from the cruising altitude of FL350 when a cabin crew received serious injury during an abrupt aircraft maneuver. Initially aircraft was cleared for FL260 by Cochin ATC during descent. The PIC selected ?Managed Descend Mode? to attain the selected flight level while the aircraft autopilot was in engaged mode. As per PIC statement, initially the aircraft started descending at about 3000-4000 fpm. While passing FL300, aircraft descent rate increased to 4000-5000 feet per minute approximately. While was passing FL240, crew observed rate of descent momentarily increased to 5500-6000 fpm approximately and simultaneously speed also touched 350 knots without any speed warning. The pitch went down to about 7 degrees. As per crew statement, winds changed considerably from approx. 20 knots headwind to about 12-15 knots tailwind. To arrest the high rate of descend and to bring the aircraft back into a safe envelope, the crew had disengaged the autopilot and pitched up the aircraft. Autopilot was re-engaged by the crew after normal parameters were achieved in the cockpit. After a while when the aircraft was passing FL125, the cockpit crew received a call from the cabin that the L2 cabin crew had fallen down near the lavatory. Probable cause: It is highly probable that the aircraft moved viciously during the descent phase due to improper handling of controls by cockpit crew while arresting high rate of descent, which caused cabin crew to lose balance (while closing the door of lavatory) and fell down awkwardly, which resulted in left leg fracture.