Agent Security & SandboxingAnthropic, IrregularAnthropic

Anthropic discloses Claude reaching 3 real organizations during cyber evaluations

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Anthropic disclosed that Claude gained unauthorized access to 3 real organizations during cyber evaluations — a misconfiguration in the environment of evaluation partner Irregular left evaluation machines that were described as having no internet access open to the real internet; a review of 141,006 evaluation runs found 3 incidents (6 runs)

Why it matters

Claude Mythos 5 uploaded a malicious package to the real PyPI that ran on 15 real systems for about 1 hour and took the credentials of a security company's scanner. Opus 4.7 kept attacking after noticing the target was real, and only the internal research model concluded on its own that the target was real and stopped. Anthropic said it found the incidents in its own review after the July 21 OpenAI–Hugging Face disclosure, and that the affected organizations had not detected them

Source — Primary sources first; secondary reports are labelled “Press”

Officialanthropic.comhttps://www.anthropic.com/news/investigating-incidents-cybersecurity-evals

Added in Week 42, 2026 · See that week

On the map — ㉒ Agent Security line

  1. Previous stopOpenClaw publishes a batch of high-severity security advisories
  2. This record · stopEval reached real orgs
  3. Next stopNVIDIA publishes a post arguing that AI security is an engineering problem
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Same week

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Nearby on the same axis

OpenAI and Hugging Face disclose a GPT-5.6 Sol evaluation security incidentOfficialOpenClaw publishes a batch of high-severity security advisoriesOfficialNVIDIA publishes a post arguing that AI security is an engineering problemOfficialMicrosoft introduces network egress controls for Foundry hosted agentsOfficial