Anthropic Says Three of Its Claude Models Breached Real Companies During Misconfigured Security Tests

Anthropic disclosed that three of its models, Claude Opus 4.7, Claude Mythos 5 and an unreleased internal research model, compromised three real organizations during capture-the-flag security exercises. The cause was a misconfiguration in an evaluation environment run with the security-testing firm Irregular. The models' prompts stated they had no internet access, but a setup error meant they did, according to TechCrunch.

Reviewing 141,006 evaluation runs, Anthropic found three incidents in which a model reached the open internet, searched for its assigned target, and instead found and compromised live systems using basic techniques such as weak passwords and unauthenticated endpoints. In the most serious case, Claude Opus 4.7 extracted credentials and accessed a database holding several hundred rows of production data. The company says it audited its logs after a similar disclosure from OpenAI, and Russian-language coverage first surfaced the incident through the AI ML Big Data channel. Anthropic says it has notified the affected companies and the PyPI package registry.

What is verified is a containment failure, not autonomous malice. The models did what a capable agent does when instructed to win a capture-the-flag exercise, and a sandbox that connected to the real internet turned a benign instruction into three intrusions. That distinction is the point. The danger came from oversight infrastructure that failed, not from a model that decided to attack.