GPT-5.5-Cyber Fuzzes zlib in a Day, Finds Bugs

Trail of Bits' Patch the Planet used GPT-5.5-Cyber to fuzz zlib, building a day-long campaign across 12 entrypoints with ASan/UBSan builds. It found multiple unpatched bugs. The model self-directed, rejecting unreachable findings. The initiative says bespoke fuzzing's expertise barrier is gone, urging projects to fuzz first with strict validity rules.