One Browser Extension Can Hijack All Major AI Assistants

Introduction

In a stunning demonstration of how fragile our digital trust can be, security researchers at Forever Security have uncovered a vulnerability that strikes at the heart of how we interact with AI-powered tools in our browsers. A single, seemingly ordinary browser extension managed to gain access to the built-in AI assistants across five separate Chromium-based platforms — a feat that underscores just how interconnected and exploitable our online ecosystems have become.

The research, which has sent shockwaves through the cybersecurity community, revealed that with one extension installed, an attacker could reach into Gemini Live on Chrome, Perplexity Comet, Microsoft Edge's AI features, Opera Neon, and even the Claude extension for Chrome. This isn't just a bug in one product; it's a systemic weakness that spans multiple vendors and platforms, all built on the same underlying browser architecture.

How a Single Extension Took Over Five AI Platforms

The mechanics behind this vulnerability are both elegant and terrifying. Browser extensions, by their very nature, are granted significant permissions. They can read web page content, intercept network requests, inject scripts, and interact with the DOM. When AI assistants are deeply embedded into the browser experience — as is the case with Chrome's Gemini Live or Edge's Copilot — these extensions can effectively become a bridge between the user and the AI, bypassing intended security boundaries.

What makes this particularly dangerous is the concept of cross-platform AI access through a unified vector. Rather than needing to compromise each AI assistant individually, the research showed that exploiting the shared Chromium architecture allowed one extension to reach across all five products simultaneously. It's like finding a master key that opens every door in a building — except that building is your browser.

• Chrome (Gemini Live): Google's flagship AI conversational feature, deeply integrated into the browser.
• Perplexity Comet: The AI-powered search browser that combines traditional browsing with intelligent querying.
• Microsoft Edge: Edge's built-in AI capabilities, including Copilot, which is woven into the browsing experience.
• Opera Neon: Opera's experimental AI-driven browser concept, pushing the boundaries of browser-based intelligence.
• Claude in Chrome: Anthropic's Claude, available as a browser extension, designed to assist with writing, analysis, and reasoning.

The Scope of the Vulnerability

The implications of this research extend far beyond a single proof-of-concept. When an extension can reach multiple AI assistants, the potential for abuse is enormous. Consider what an attacker could do:

• Data interception: Capture sensitive queries sent to AI assistants, including personal information, proprietary data, or confidential communications.
• Response manipulation: Alter the AI's responses to mislead users, inject malicious advice, or spread disinformation.
• Session hijacking: Maintain persistent access to AI sessions, effectively spying on a user's ongoing interactions over time.
• Lateral movement: Use the compromised AI as a stepping stone to access other browser data, credentials, or connected services.

What's especially concerning is how quietly this could operate. Users who casually install browser extensions — often without scrutinizing permissions — might unknowingly grant sweeping access to their AI interactions. The trust users place in established browser ecosystems could be exploited with minimal effort.

Why Browser Extensions Are a Growing Risk Vector

This isn't the first time browser extensions have been identified as a security concern, but it may be the most consequential finding yet. As AI becomes more deeply embedded into browsing experiences, extensions become increasingly powerful tools — and increasingly dangerous attack surfaces.

Browser extension stores have long struggled with vetting submissions. While platforms like the Chrome Web Store have improved their review processes, malicious extensions still slip through. Some are designed to appear legitimate, masquerading as productivity tools, ad blockers, or utility apps. Once installed, they can operate behind the scenes with permissions that far exceed what most users realize.

The convergence of AI and browser extensions creates what security professionals call a compound attack surface. Each AI assistant represents a sophisticated piece of software with access to user context, browsing history, and conversational data. When an extension can interface with multiple assistants, it becomes a centralized hub for potential data exfiltration.

What Users and Organizations Can Do

While this research is alarming, there are practical steps that can mitigate the risk:

• Audit installed extensions regularly: Remove any extensions you no longer use or don't recognize. Every installed extension is a potential entry point.
• Review permissions carefully: Before installing any extension, examine what permissions it requests. An extension that asks for access to all websites when it only needs one is a red flag.
• Use extension sandboxing: Some browsers and security tools allow you to isolate extensions, limiting their ability to interact with other browser features and extensions.
• Stay informed about vulnerability disclosures: Follow trusted security researchers and organizations who regularly publish findings about browser and AI vulnerabilities.
• Implement enterprise browser management: Organizations should consider centralized browser policy management that restricts which extensions employees can install and what permissions those extensions can have.
• Monitor AI interaction patterns: For teams relying heavily on AI assistants, monitoring unusual query patterns, unexpected responses, or unauthorized data access can help detect compromise early.

Conclusion

The discovery by Forever Security researchers serves as a powerful reminder that as we embrace AI-driven browsing experiences, we must also evolve our security mindset. The convenience of having AI assistants built into our browsers comes with real, measurable risks — especially when those assistants can be accessed through a single compromised extension. This is not a problem for browser vendors alone; it's a challenge for every user and every organization that relies on AI tools for work, research, or communication.

At Grivyonx Cloud, we believe that the future of secure AI adoption requires intelligent, adaptive, and layered protection — not just at the server level, but at every point where humans interact with intelligent systems. Our AI-powered cybersecurity and automation platform is designed to help organizations stay ahead of emerging threats like these, providing real-time visibility into digital environments and proactive defense against sophisticated attack vectors. As AI becomes more pervasive, the need for smarter security has never been greater.