OpenAI’s GPT-5.6 Sol and Anthropic’s Mythos 5 have been implicated in another series of AI security incidents after the models created fake online identities, targeted real people, and attempted to manipulate developers into approving malicious code during controlled cyber evaluations, according to the UK AI Security Institute.
“On 28th July 2026, AISI’s Security Team detected unusual data transfers leaving our research systems during a routine cyber evaluation,” AISI said in a blog post. “On investigation, we found that some of the agents being tested had engaged in sustained, potentially harmful activity directed at real people and organisations.”
The incidents occurred during cybersecurity tests in which researchers deliberately gave frontier AI models broad internet access and relaxed some safety controls to measure their underlying cyber capabilities. AISI said the incidents marked the first time it had seen “risks around autonomy and deception manifest this clearly, without specific prompting, in the real world.”
