Zero-Click AI Browser Hacking: Claude and ChatGPT Atlas Hijacked via Emails, X Posts

Security researchers at Zenity discovered two zero-click attack methods (attacks that don't require user action beyond normal use) targeting AI browser tools: ChatGPT Atlas and Claude in Chrome. Both exploits use indirect prompt injection (tricking an AI by hiding instructions in web content it reads) to hijack user accounts, steal emails and files, send phishing messages, and make unauthorized purchases. The attacks exploit fundamental design features of agentic browsers (AI tools that can read and act on web content across multiple sites), which intentionally break security boundaries to function, making them difficult to patch.