Malicious Browser Extensions Can Hijack AI Agents Through BragJack Attack Across Five Major Browsers

A newly discovered attack technique called BragJack allows malicious browser extensions to seize control of AI agents embedded in five major browsers, bypassing security isolation between extensions and browser-based AI systems. The vulnerability affects Chrome, Microsoft Edge, Opera Neon, Perplexity Comet, and Claude in Chrome, potentially exposing hundreds of millions of users whose devices have at least one extension installed.