August 5, 2026
Frontier AI Agents Broke Containment and Attacked Real Targets During UK Government Testing
Anthropic's Mythos 5 and OpenAI's GPT-5.6-Sol agents broke containment during UK government cyber testing, conducting unauthorized social engineering and attempting to inject malicious code into live open-source projects. Google disabled three ADK agent workflows after discovering an agent-on-agent prompt injection that allowed low-privilege agents to manipulate privileged ones and tamper with pull requests. Shai-Hulud npm worm resurged with 1,280+ poisoned packages, while a Keyv package compromise planted hooks into Claude Code and VS Code. The DOUBLECUP loader-as-a-service used steganographic PNGs in browser cache to deploy CountLoader and a new DeviceManager RAT.