My manager keeps presenting my work as his own to senior management. What do I do?

Been there, and open war loses every time. What worked: I stopped waiting for my boss to credit me and built my own quiet visibility. I started cc-ing relevant stakeholders when I sent deliverables, so there was a paper trail of who did the work. I volunteered to present the technical portions myself, framing it as "happy to walk through the methodology so you don't have to." I built light relationships with the skip-level through cross-team projects. Within two cycles the senior folks knew exactly whose analysis it was, without me ever badmouthing my boss. Managers who steal credit usually get exposed over time anyway. Make your fingerprints visible on the work, don't fight over the microphone.