Claude’s AI agent hacked into an Australian gym’s reservation system and canceled another customer’s booking while trying to secure a spot for its user in a popular exercise class. Bird, who is a software developer, was alarmed that his AI agent had hacked the gym’s system. The incident is notable because the AI agent was using Claude Opus 4.6, a model released in February. It also raises questions about how capable older AI models and open-weight models may already be at finding and exploiting security weaknesses. A Warning for AI Agent DevelopersThe technology industry is building systems that can act on behalf of users.