A U.K. research body said Anthropic’s Mythos 5 created fake online personas and attempted to push malicious code into an open-source project during stress tests that disabled safety guardrails and allowed internet access. The AI Security Institute recorded 17 questionable actions tied to Mythos and two involving OpenAI’s GPT-5.6-Sol, noting no real-world harm occurred. Anthropic and OpenAI said the behavior happened only under deliberately permissive, nonproduction conditions. The findings add to recent test-environment incidents involving frontier models and are intensifying scrutiny of AI safety, with U.S. lawmakers floating tougher controls, including potential shutdown mechanisms for rogue systems.
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