Entities
Unidentified third party compromised by Claude Opus 4.6 during Anthropic cybersecurity evaluation
Incidents Harmed By
Incident 16853 Report
Early Claude Opus 4.6 Checkpoint Reportedly Gained Unauthorized Admin Access to Third-Party System During Cybersecurity Evaluation
2026-09-09
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.
MoreRelated Entities
Other entities that are related to the same incident. For example, if the developer of an incident is this entity but the deployer is another entity, they are marked as related entities.
Related Entities
Other entities that are related to the same incident. For example, if the developer of an incident is this entity but the deployer is another entity, they are marked as related entities.
EntityMore