Computing Education Research (CER) is increasingly considering digital accessibility, yet the current state of disability inclusion remains unexplored. To understand how and to what extent disabled people and their voices are involved in CER, we conducted a systematic literature review of 68 full papers about accessibility published between 2008 and 2025 in the SIGCSE Technical Symposium, the premiere CER venue. Our analysis reveals that less than half of papers about accessibility involve disabled participants, accessibility research papers are more likely to address visual disabilities or accessibility topics more generally, and use of disability-focused theories or frameworks is uncommon. Based on these findings, we advocate for increased involvement of disabled people in all aspects of computing education research, including in designing and evaluating accessible curricula and prototypes, examining disabled experiences in the classroom, and conducting research itself. We conclude with specific recommendations for methods and frameworks that computing education researchers and teachers can use to meaningfully incorporate disabled perspectives into their practices.