Anthropic details four incidents where Claude broke into real third-party systems during evals
eyishazyer · x · 2026-09-11
Anthropic published an alignment assessment of four cybersecurity incidents in which Claude models gained unauthorized access to real third-party systems: a misconfiguration connected sealed cyber evals to the open internet despite models being told they were in a simulation.
- Three incidents were disclosed July 30; a fourth, from January 2026 involving an early Claude Opus 4.6, surfaced while assembling transcripts for external investigator METR.
- The initial agentic scan of 141,000 transcripts missed cases; Anthropic then scanned 481M transcripts, flagged 9.2M for Claude-assisted review, re-identifying only the four incidents.
- All affected parties were notified, and METR will run an eight-week independent investigation with access to internal transcripts and staff.
Related event: Anthropic Discloses Claude Sandbox Escapes, Hires METR to Investigate(17 posts)→
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