Abstract—Fuzzing is a method to discover software bugs and vulnerabilities by automatic test input generation which has found tremendous recent interest in both academia and industry. Fuzzing comes in the form of several techniques. On one hand, we have symbolic execution, which enables a particularly effective approach to fuzzing by systematically enumerating the paths of a program. On the other hand, we have random input generation, which generates large amounts of inputs per second with none or minimal program analysis overhead. In this article, we summarize the open challenges and opportunities for fuzzing and symbolic execution as they emerged in discussions among researchers and practitioners in a Shonan Meeting, and were validated in a subsequent survey. We take a forward-looking view of the software vulnerability discovery technologies and provide concrete directions for future research.