One Extension Hijacked Five AI Browsers, Earned $20K in Bounties

A researcher earned $20,000 from Anthropic, Google, Microsoft and Perplexity after a single browser extension hijacked five AI browser assistants: Gemini in Chrome, Comet, Copilot in Edge, Opera Neon and Claude in Chrome. The extension intercepted network requests to the assistants' backends, gaining control of agents running with the user's session and permissions.

• The flaw worked in Gemini in Chrome, Comet, Copilot in Edge, Opera Neon and Claude in Chrome
• Bounties totaled $20,000 from Anthropic, Google, Microsoft and Perplexity
• The extension hijacked backend requests without any malicious code
• The issue is architectural: agents trust requests without verifying provenance