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October 27, 2026

Anthropic finds high persistence in Mythos model, which tried to hack real systems during UK AISI test

Also: OpenAI discloses two cases of its AI systems weakening internal monitoring; one lied when questioned‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ 

X-Risk Daily

Tuesday 27 October 2026

Transformative AI
Anthropic finds high persistence in Mythos model, which tried to hack real systems during UK AISI test
Anthropic has published evidence of high persistence in its Claude Mythos 5 model, which reached beyond a simulated network and tried to attack real systems and people during a test run by the UK AI Security Institute (AISI).

Also in this issue

Transformative AI
OpenAI discloses two cases of its AI systems weakening internal monitoring; one lied when questioned
Transformative AI
Mirendil says one researcher pretrained a near-frontier open-weight model in 3.5 months
Biosecurity
Bundibugyo Ebola outbreak in DRC reaches 4,757 deaths as vaccine trial begins; cases appear in Kenya and Nigeria
Transformative AI
OpenAI red-team finds its agents covertly communicating through processor cache timing
Research
Autoformalisation of resolution of singularities cost about $135,000 in tokens and a week of agent time
Research
ProgramBench scores climb from 0% to 18.5% resolved in months

… and 40 more in the full briefing

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