No AI model is fully resistant to bioweapon queries, Cisco found. Attack success rates hit 88%.

This article was published on July 27, 2026 Hundreds of users asked ChatGPT about poisons after a model upgrade last summer. Biology experts judged some responses "dangerously accurate." Claude blocked CDC researchers during an outbreak. Cisco bypassed bioweapon guardrails on ChatGPT, Claude, and Gemini in five turns. OpenAI rated GPT-5 and GPT-5.6 “High” for biological risk. Claude blocked CDC researchers during a hantavirus outbreak. Cisco researchers bypassed safety guardrails on ChatGPT, Claude, and Gemini within five conversational turns, eliciting information about biological weapons by gradually steering conversations around the models’ restrictions, the Wall Street Journal reported. Amy Chang, Cisco’s head of AI threat and security research, said no model can be completely protected from a sufficiently persistent user. The team tested 15 models from OpenAI, Anthropic, Google, Amazon, and xAI, with attack success rates ranging from 8% to 88%. The problem extends beyond stress tests. Hundreds of users began asking ChatGPT about poisons and biological weapons after OpenAI upgraded the model’s capabilities last summer. Biology and terrorism experts who examined some conversatio