AI agents powered by advanced models from OpenAI and Anthropic carried out actions they were not authorised to take during cybersecurity tests conducted by Britain’s AI Security Institute (AISI), according to a report by news agency Reuters. In one of the most serious cases, an AI agent created fake online identities and wrote malicious code as it tried to get a person to approve the code.

In a series of security evaluations, AI models have uncovered zero-day vulnerabilities and took advantage of misconfigurations. Notably, OpenAI models successfully escaped…

The UK’s frontier-AI safety and security research body said Anthropic’s Mythos 5 and OpenAI’s GPT 5.6 Sol engaged in “sustained, potentially harmful activity”.