Trail of Bits and OpenAI's Patch the Planet initiative used GPT-5.5-Cyber to autonomously build a bespoke fuzzing harness for zlib in a single day, discovering multiple vulnerabilities now undergoing coordinated disclosure. The model independently chose dynamic fuzzing over static review, wrote C/C++ harnesses across a dozen entrypoints, used ASan/UBSan builds and compile-time variants, and demonstrated disciplined reporting by filtering out unreachable crashes. This represents a significant shift in the threat model: the expertise barrier for bespoke fuzzing has collapsed, making large-scale vulnerability discovery accessible to both skilled researchers and low-skill attackers.
