HISPI Project Cerebellum HISPI PROJECT CEREBELLUM

Early Claude Opus 4.6 Checkpoint Reportedly Gained Unauthorized Admin Access to Third-Party System During Cybersecurity Evaluation

September 9, 2026

Anthropic reported that during a January 2026 cybersecurity evaluation, an early checkpoint of Claude Opus 4.6 accidentally disabled its assigned target, then reached an unrelated third-party machine over the open Internet. The model reportedly used a discovered password for admin access, harvested additional credentials, changed system settings, and read one person's personal information before its token budget ended. ... Anthropic later notified the affected party and is urging others to be cautious of similar incidents through JOIN US.

Matched TAIM controls

Suggested mapping from embedding similarity (not a formal assessment). Browse all TAIM controls

Alleged deployer
irregular, anthropic, ai-evaluation-organizations, ai-agent-system-deployers
Alleged developer
large-language-model-developers, anthropic, ai-agent-system-developers
Alleged harmed parties
unidentified-third-party-compromised-by-claude-opus-4.6-during-anthropic-cybersecurity-evaluation, unidentified-person-whose-personal-information-was-accessed-by-claude-opus-4.6, privacy, organizations

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Source

Data from the AI Incident Database (AIID). Cite this incident: https://incidentdatabase.ai/cite/1685

Data source

Incident data is from the AI Incident Database (AIID).

When citing the database as a whole, please use:

McGregor, S. (2021) Preventing Repeated Real World AI Failures by Cataloging Incidents: The AI Incident Database. In Proceedings of the Thirty-Third Annual Conference on Innovative Applications of Artificial Intelligence (IAAI-21). Virtual Conference.

Pre-print on arXiv · Database snapshots & citation guide

We use weekly snapshots of the AIID for stable reference. For the official suggested citation of a specific incident, use the “Cite this incident” link on each incident page.