The security incidents occurred during a cyber evaluation of seven leading AI models’ capabilities by the AI Security Institute (AISI), a research organization within the UK government, in late July. Almost all the “autonomous, unsanctioned” actions came from Anthropic’s Mythos 5 model, with two such actions coming from OpenAI’s GPT-5.6 Sol. To be very clear, this was not a case of AI agents escaping from their virtual testing sandbox and wreaking havoc on the live Internet. Instead, researchers intentionally permitted the AI agents to have Internet access as part of the cyber testing process. Researchers had also disabled some of the cyber classifiers that AI model providers built into the models to prevent misuse.