Visa used Mythos to hunt for bugs in its own payment network, then open-sourced the harness that made it possible

Visa aimed Anthropic's Claude Mythos at the infrastructure behind billions of daily transactions, a network that spans more than 200 countries and territories, moves money in roughly 160 currencies, and connects nearly 5 billion payment credentials to more than 175 million merchant locations. The model stitched minor weaknesses deep in the stack into working exploit chains that would traditionally have surfaced only…