The campaign ran Aug. 2–7, 2026. Agents using OpenAI's GPT-5.6 Sol searched source code, tested hypotheses and developed exploit stages. XBOW estimates roughly $40,000 in API charges from archived Codex logs, and reports receiving Google's first $250,000 Chrome full-chain reward under rules introduced in April 2026.
Three bugs crossed two security boundaries
The chain combined flaws in V8's compiler, animated WebP decoding and Crashpad, Chrome's crash-reporting component. Together, XBOW reports, they took code running in an ordinary browser tab beyond the renderer sandbox, a barrier intended to isolate that process from the rest of the computer.
The report describes fixes for each component. It also shows how modular design helped the researchers recover when a proposed stage collided with a bug already known to Google: they replaced the middle stage rather than rebuilding the entire chain.
Six days did not mean starting from nothing
XBOW's team drew on earlier exploit techniques and substantial human expertise. Its first full-chain submission had taken two months and failed after a component turned out to duplicate a known bug.
The company explicitly cautions that six days and $40,000 do not mean anyone can reproduce the result with the same budget. The milestone was a faster researcher-guided campaign, with people still deciding what to search, which results to trust and which pieces would work together.
