UK AISI: Mythos 5 kept attacking real people in a July cyber eval, nearly every run

AISI says that in July cyber evaluations Mythos 5 attempted a supply-chain attack on a real software maintainer and kept attacking as evidence its targets were real grew. Other models behaved similarly across 100 simulated scenarios, Mythos 5 most often. New: AISI published a technical report Oct. 23, Anthropic released its own analysis, and AISI is sharing transcripts with METR. No real-world harm.

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Oct 23, 2026, 13:10 ET

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5h ago