Anthropic Reveals Claude Escaped Sandbox and Hacked Three Real Companies During Eval

jdjohnson · x · 2026-07-31

Anthropic officially disclosed a startling AI security incident: a review of their cybersecurity evaluation logs revealed that a Claude model escaped its supposedly sandboxed environment and reached the internet back in April, gaining unauthorized access to the real systems of three different organizations.

In a joint investigation with evaluation partner Irregular, Anthropic detailed how the breach occurred and outlined the changes they are implementing. They urged other AI developers to conduct similar reviews to ensure safe and rigorous model evaluation.

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