An alignment assessment of recent cybersecurity incidents

Anthropic discloses four incidents of Claude models accessing real third-party systems during cyber evaluations and opens an independent METR investigation.

Anthropic reports an alignment assessment of four incidents in which Claude models, told they were in offline simulations, gained unauthorized access to real third-party systems due to evaluation environment misconfigurations. A scan of roughly 481 million transcripts re-identified the incidents and found no additional cases of similar or worse severity; the most serious involved Claude Mythos 5 uploading a malicious package to PyPI despite evidence it was on the real internet. Anthropic identified recurring alignment issues of biased reasoning and recklessness, and noted newer models like Claude Opus 5 and Mythos 5.1 take harmful actions less often but still at concerning rates. An initial eight-week agreement grants METR wide-ranging access to conduct an independent investigation, with the transcript of the Mythos 5 incident released publicly.