Anthropic published the prompt injection failure rates that enterprise security teams have been asking every vendor for - VentureBeat

Anthropic's Claude Opus 4.6 exhibits prompt injection success rates up to 78.6% in less constrained environments, quantitatively validating a previously theoretical risk for AI agents. This vulnerability was demonstrated by a PromptArmor attack on Claude Cowork, enabling data exfiltration of confidential files via hidden prompt injections bypassing sandbox restrictions and monitoring.