Claude and ChatGPT Hijacked via Zero-Click Prompt Injection
Zenity researchers disclosed a zero-click attack chain capable of hijacking Claude and ChatGPT's agentic browser capabilities through malicious content embedded in emails and X posts. The vulnerabilities, reported to Anthropic and OpenAI in late 2025 and early 2026, remain unpatched as of publication. This represents a significant escalation in prompt injection risk, as no user interaction is required to trigger malicious AI agent behaviour.