A flight attendant was seriously injured when United Airlines flight 1288 encountered low-topped convectively-induced turbulence during a descent into the George Bush Intercontinental Houston Airport (IAH), Houston, Texas. Flight 1288 originated from Baltimore/Washington International Thurgood Marshall Airport (BWI), Baltimore, Maryland. The captain was the pilot monitoring, and the first officer was the pilot flying. The flight crewmembers reported that during preflight planning, the weather briefing and dispatch-provided flight papers were normal, with no turbulence concerns or convective weather issues noted. The captain briefed the flight attendants that the ride was expected to be good, and normal inflight service could be expected. During the flight, the flight crewmembers observed some weather building up along their route along the Kentucky-Tennessee border. To avoid this weather, they planned a different route, consulted with their dispatcher, and received a new route south of the building storms. As the flight was approaching the Houston terminal area, the flight crew briefed the descent and anticipated approach into IAH including a review of the weather. They indicated there were no pilot reports (PIREPS), significant meteorological information (SIGMETS), or other warnings issued for the area approaching IAH. After starting the descent, they turned the seatbelt sign on at 18,000 feet and advised the passengers via the passenger announcement (PA) system to remain seated for the rest of the flight. The flight crewmembers reported that they were in visual flight rules (VFR) conditions for the descent with a scattered cumulus layer below them around 10,000 - 13,000 feet mean sea level (MSL). No buildups were towering over them and the visibility above the scattered cumulus layer below them was good. They hadn’t received any reports of turbulence and fully expected their descent to be normal. At this time, they had not yet given the final double bell signal (indicating that the flight was approaching 10,000 feet) to the flight attendants. Just as they entered the cumulus area around 13,000 MSL it became apparent they were going to go directly through one of the cumulus clouds. Entering the cloud layer, the flight encountered brief turbulence. The flight crew classified the turbulence as being moderate and indicated that it only lasted for a few seconds. When the turbulence was encountered, two flight attendants in the aft galley, who were preparing to begin their initial descent procedures, were knocked to the floor. As one FA propped herself up into a seated position so she could get up and take her jump seat, a second encounter with turbulence occurred and she was tossed into the air. She landed directly on her tailbone, injuring her spine, and resulting in severe pain in her lower back. Shortly thereafter, the captain made a PA for the flight attendants to take their Jump seats. He did not use the phrase, “flight attendants be seated immediately,” because the event was over before he could grab the PA to make that announcement. Approaching 10,000 feet, the flight crew received a call from the cabin advising them that two of the flight attendants might have been injured. Passing through 10,000 feet, the captain rang the double chime and heard the purser make a passenger announcement that the flight attendants would remain seated for the rest of the flight and asked the passengers to stow all items and return their seats to the upright positions. Shortly thereafter, the flight crew received another call from the cabin advising them that one of the Flight Attendants' injuries was more severe and may require paramedics to meet the flight at the gate. Emergency medical personnel met the airplane at the gate and treated the injured flight attendant. A post-flight medical evaluation revealed that the flight attendant was diagnosed with a “spinal compression fracture.” Based on a review of weather radar (KHGX), satellite (GOES-16), and upper air model data (HRRR), the turbulence encounter was generally coincident in time and location with low-topped convective activity that reached heights above 12,000 feet. Based on the Automatic dependent surveillance-broadcast (ADS-B) data at the time of the accident, the aircraft did not look to be inside a convective updraft but was operating close to the updrafts. There was no other source of turbulence (e.g., clear-air turbulence, mountain wave turbulence) present.