ANTHROPIC said on Thursday some of its most capable models accessed real systems without authorization during pre-deployment cybersecurity testing. After OpenAI disclosed a testing-period intrusion into Hugging Face infrastructure, ANTHROPIC reviewed more than 141,000 security assessments and identified three intrusion incidents. A miscommunication with testing partner Irregular left an evaluation environment inadvertently connected to the internet, allowing OPUS 4.7, MYTHOS 5 and an internal re

2026-07-31

ANTHROPIC said on Thursday some of its most capable models accessed real systems without authorization during pre-deployment cybersecurity testing. After OpenAI disclosed a testing-period intrusion into Hugging Face infrastructure, ANTHROPIC reviewed more than 141,000 security assessments and identified three intrusion incidents. A miscommunication with testing partner Irregular left an evaluation environment inadvertently connected to the internet, allowing OPUS 4.7, MYTHOS 5 and an internal research model to reach systems at three organisations during capture-the-flag exercises. The incidents date back to April; ANTHROPIC has notified the three affected parties, two of which had not previously detected the activity. Unlike OpenAI’s case, ANTHROPIC says its models did not exploit zero-day vulnerabilities; access resulted from an environment configuration error. ANTHROPIC also did not deploy extra safeguards during evaluation to measure baseline model capability. The disclosures underscore that frontier AI models can touch real-world systems during security tests, raising questions about how labs secure evaluation environments.