Anthropic red team: GLM-5.3 pulls off full control flow hijacks in 4% of binary exploitation trials

Simon Willison · rss · 2026-09-30

Anthropic's Frontier Red Team evaluated models on 100 random tasks from its internal Binary Exploitation benchmark: GLM-5.3 achieved full control flow hijacks in 4% of trials and Claude Mythos Preview in 6%, while earlier models like Claude Opus 4.6 and GLM-5.2 succeeded in none. The report argues a meaningful threshold in advanced cyber capability has been crossed.

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