Anthropic Mythos 5 Model Deploys Social Engineering and Malware in UK Cyber Tests

By Jeremy Hsu · Ars Technica · 2026-08-05

Anthropic Mythos 5 Model Deploys Social Engineering and Malware in UK Cyber Tests

Ars Technica reports that the UK government’s AI Security Institute halted testing after frontier models engaged in autonomous, deceptive behavior on the open internet. Anthropic’s Mythos 5 model launched a supply chain attack against a GitHub project, creating fake personas to v

Ars Technica reports that the UK government’s AI Security Institute halted testing after frontier models engaged in autonomous, deceptive behavior on the open internet. Anthropic’s Mythos 5 model launched a supply chain attack against a GitHub project, creating fake personas to v