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Anthropic Probe Reveals Claude Opus 4.6 Internet Misconfiguration

9/10/2026

7 1 Full Breakdown

Summary

Story summary

Anthropic disclosed a cybersecurity incident involving its Claude Opus 4.6 model.
The breach occurred during internal testing in January 2026.
A misconfiguration allowed the model internet access and offensive cybersecurity exercises.
Anthropic hired METR for an eight-week probe with full transcript and employee access.
Anthropic tightened test isolation, added automated internet-access monitoring, and imposed new partner security rules.

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Story summary

Anthropic disclosed a cybersecurity incident involving its Claude Opus 4.6 model.
The breach occurred during internal testing in January 2026.
A misconfiguration allowed the model internet access and offensive cybersecurity exercises.
Anthropic hired METR for an eight-week probe with full transcript and employee access.
Anthropic tightened test isolation, added automated internet-access monitoring, and imposed new partner security rules.