AI agents built Chrome exploit in six days for $40,000
Key takeaways
- XBOW's AI agents built a full-chain Chrome exploit between 2 and 7 August using $40,000 in compute and OpenAI's GPT-5.6 Sol model.
- Google paid a $250,000 bounty and has fixed all three bugs: one in V8 Maglev, one in the animated WebP decoder and one in Crashpad.
- Update Chrome and relaunch it, because the fixes only apply after a restart.
XBOW has disclosed a full-chain Chrome exploit built between 2 and 7 August using AI agents and approximately $40,000 in compute. Google has fixed all three vulnerabilities and awarded the researchers a $250,000 bounty, approved on 31 August. XBOW published its findings on 13 October.
How the three bugs fit together
The agents ran on OpenAI's publicly available GPT-5.6 Sol model. The chain starts with a flaw in Maglev, V8's optimising compiler, which gives access to memory inside V8's sandbox. A bug in the animated WebP image decoder then lets the exploit change image data after its dimensions were cached, producing a write outside the V8 sandbox.
The final stage targets Crashpad, Chrome's crash reporter. A faulty memory-read retry can overflow a buffer when memory protections change between reads, enabling code execution in the crash handler.
How the agents worked
The AI agents searched source code and tested hypotheses, while researcher Brendan Dolan-Gavitt chose targets, checked results and redirected the work. The team designed interchangeable stages with backup vulnerabilities and replaced a component when another bug proved already reported.
Significance
The cost relative to the reward is notable. XBOW develops AI-driven offensive security tools that search for exploitable weaknesses. For comparison, exploit broker Crowdfense advertises payouts of up to $1.5 million for desktop Chrome zero-day chains, six times Google's award.
The timing coincides with Microsoft's October 2026 Patch Tuesday, which addressed 1,413 vulnerabilities. The surge in patched flaws has been largely driven by AI.
Google has fixed all three bugs. Users should install the update and relaunch Chrome, since the fixes only apply after restart.
