Seattle – October 14, 2026 -- Chainguard has launched Chainguard Harness, a cyber harness that runs frontier AI models such as Anthropic's Claude Mythos 5.1 against a live build of a customer's application and delivers only reproduced vulnerabilities, each paired with an engineer-reviewed fix. The product is available through the Claude Marketplace by Anthropic, so enterprises can buy it with their existing Anthropic commitment.