B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Total 19000
Situational Awareness
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Regained Aircraft Control; Flight Crew Returned To Clearance
Weather
[ZZZ] to PHL. Many thunderstorms enroute. Flight plan and path went up the east coast over land; no water routes. Aircraft was dispatched with a light load of passengers and 41;000 feet final altitude. Our path paralleled some of these fronts carrying thunderstorms and convective activity. 30NW of SAV we were on top of this weather above a solid layer. We met an updraft of air that took us up to an altitude 41;500 feet in what we considered severe turbulence. Airspeed over speed was encountered; then an under speed was [encountered] with this upset recovery. A request for lower was [made] and [we were] given 37;000 feet. Leveling 37;000 feet the autopilot was turned back on and a verification of status of flight attendants and people were made to see anyone was hurt. Nobody was hurt.Flying among huge unstable weather masses. Even though we had the weather radar on and the turbulence was not being depicted we still encountered rough air. If I could re-do this I would have stayed at a lower altitude and given a wider berth to the weather. Also; I would have asked ATC for more updates on their ride reports and paths that traffic in front was using to get around some of the weather.
B737-800 Captain reported airspeed and altitude excursions occurred during severe turbulence at FL410 while skirting thunderstorms.