This paper presents a systematic mapping study of the research on crowdsourced security vulnerability discovery. The aim is to identify aspects of bug bounty program (BBP) research that relate to product owners, the bug-hunting crowd or vulnerability markets. Based on 72 examined papers, we conclude that research has mainly been focused on the organisation of BBPs from the product owner perspective, but that aspects such as mechanisms of the white vulnerability market and incentives for bug hunting have also been addressed. With the increasing importance of cyber security, BBPs need more attention in order to be understood better. In particular, datasets from more diverse types of companies (e.g. safety-critical systems) should be added, as empirical studies are generally based on convenience sampled public data sets. Also, there is a need for more in-depth, qualitative studies in order to understand what drives bug hunters and product owners towards finding constructive ways of working together.