B737 MAX 8 Captain reported encountering wake turbulence in cruise flight at FL260 that resulted in minor injuries to a Flight Attendant.

Narrative

Houston Center vectored us off our en route course to join the BAYYY Arrival due to crossing traffic. This traffic was 20 to 40 miles in front of us crossing from left to right. Ride had been smooth and we were approximately 75 miles from top of descent. The headwind was strong; about 90 knots. Without any warning; we experienced a wake turbulence event that was abrupt and significant enough to disconnect the autopilot. After we recovered; Pilot Monitoring checked on cabin crew/passengers. A Flight Attendant had been thrown to the floor and complained of pain in her hip and elbow. We asked if we could provide any assistance and/or have someone meet us at the gate. Injured attendant declined. After the flight; Pilots debriefed the cabin crew on what had transpired and inquired as to any concerns from passengers (there were none).I believe this event was the result of lack of vision. As Pilot Monitoring; I didn't consider that although the traffic was far away; the strong headwind pushed the wake turbulence into us in an unexpected location. I will bring this into my assessment in future traffic crossings.