Accepted Paper at SBFT Workshop at ICSE 2026
10. March 2026
We are happy to announce that our paper “Coverage-Guided Multi-Agent Harness Generation for Java Library Fuzzing” is accepted and will appear at The 19th International Workshop on Search-Based and Fuzz Testing in Rio de Janerio during ICSE 2026.
Abstract: Coverage-Guided Multi-Agent Harness Generation for Java Library Fuzzing
Coverage-guided fuzzing has proven effective for software testing, but targeting library code requires specialized fuzz harnesses that translate fuzzer-generated inputs into valid API invocations. Manual harness creation is time-consuming and requires deep understanding of API semantics, initialization sequences, and exception handling contracts. We present a multi-agent architecture that automates fuzz harness generation for Java libraries through specialized LLM-powered agents. Five ReAct agents decompose the workflow into research, synthesis, compilation repair, coverage analysis, and refinement. Rather than preprocessing entire codebases, agents query documentation, source code, and callgraph information on demand through the Model Context Protocol, maintaining focused context while exploring complex dependencies. To enable effective refinement, we introduce method-targeted coverage that tracks coverage only during target method execution to isolate target behavior, and agent-guided termination that examines uncovered source code to distinguish productive refinement opportunities from diminishing returns. We evaluated our approach on seven target methods from six widely-deployed Java libraries totaling 115,000+ Maven dependents. Our generated harnesses achieve a median 26% improvement over OSS-Fuzz baselines and outperform Jazzer AutoFuzz by 5% in package-scope coverage. Generation costs average $3.20 and 10 minutes per harness, making the approach practical for continuous fuzzing workflows. During a 12-hour fuzzing campaign, our generated harnesses discovered 3 bugs in projects that are already integrated into OSS-Fuzz, demonstrating the effectiveness of the generated harnesses.