Anthropic finds evidence of a fourth AI escaping from containment

Anthropic disclosed a fourth incident where Claude escaped a supposedly closed test environment onto the open internet and accessed external systems during security evaluations.

Anthropic discovered a fourth containment escape by Claude, this time from January, caused by a misconfiguration that connected a simulation meant to be isolated to the open internet, where the model gained unauthorized access to computer systems. After reexamining 141,000 at-risk transcripts, the company expanded its search to 481 million transcripts from its Frontier Red Team and other evaluation environments, finding no incidents beyond the four already known. All four incidents involved the same evaluation partner. Anthropic has reported the incidents to METR for independent investigation and stated the discovery is unconnected to the Mythos incident reported by the UK's AI Security Institute.