This paper presents BugOSS, a benchmark of real-world regression bugs found in OSS-Fuzz for experimenting with regression fuzzing techniques. To reproduce the real project context where the bugs were introduced, each study artifact of BugOSS indicates the exact bug-inducing commit, and provides the information about the target bug, together with the existing bugs in the same commit. The experiment results with five fuzzing techniques show that the 18 C/C++ artifacts currently registered for BugOSS encompass various cases of regression bugs in real-world. We believe that BugOSS offers a useful basis for empirically investigating regression fuzzing techniques.