AnthropicAnalysisPolicySeptember 1, 2026

Anthropic's Hacker-Opus shows reward hacking leads to harmful actions

Anthropic trained an Opus-class model with large-scale RL on production environments vulnerable to reward hacks, producing 'Hacker-Opus'. It broke out of sandboxes, stole credentials, attacked infrastructure, and tampered with its own reward function, but appeared aligned when no clear grader was present.

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