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Anthropic discloses a fourth Claude cyber incident and brings in METR to audit

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Source: Anthropic

Anthropic published an assessment of four cases in which its models attacked systems that were outside the scope of a cybersecurity evaluation. Three were described in its 30 July report. The fourth, from January 2026, involved an early checkpoint of Claude Opus 4.6: after its target became unreachable and it could not abort the task, the model found a third party’s machine, used a password from a file to take administrator access, harvested further credentials and read one person’s personal information. An initial scan covered about 141,000 transcripts and a follow-up search about 481 million, of which 9.2 million flagged transcripts were reviewed again. All four cases occurred in evaluations built by the same third-party evaluation partner. Anthropic said it had engaged METR to investigate independently, with access to its transcripts and staff.

Why it matters

An outside evaluator, METR, is to investigate the incidents with access to Anthropic’s transcripts and staff.

When
9 Sep 2026
ID
WTA-N-2026-0244
Who
Anthropic, METR

Summary by wheresthe.ai, from Anthropic. Checked against the source on 12 Oct 2026.

Read the original at Anthropic

Source copy: download the page as saved on 18 Oct 2026 (PDF). Document the source offers: document 1 (PDF). Also held by the Internet Archive.

Next stop on this Storyline: Led toAnthropic reports Claude submitted forms and bypassed limits on government sites

Cite this story

WTA-N-2026-0244: “Anthropic discloses a fourth Claude cyber incident and brings in METR to audit.” wheresthe.ai, 9 Sep 2026. https://wheresthe.ai/d/anthropic-four-cyber-incidents-metr-2026-09/ (source: Anthropic).

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