Millions of users may have unknowingly exposed their most private conversations with AI tools after cybersecurity researchers uncovered a network of browser extensions quietly harvesting and selling chat data.Here’s a reminder many people forget: an AI assistant is not your friend, not a financial expert, and definitely not a doctor or therapist. It’s simply someone else’s computer, running in a data center and consuming energy and water. What you share with it matters.

That warning has taken on new urgency after cybersecurity firm Koi uncovered a group of Google Chrome extensions that were quietly collecting user conversations with AI tools and selling that data to third parties. According to Koi, “Medical questions, financial details, proprietary code, personal dilemmas,” were being captured — “all of it, sold for ‘marketing analytics purposes.’”

This issue goes far beyond just ChatGPT or Google Gemini. Koi says the extensions indiscriminately target multiple AI platforms, including “Claude, Microsoft Copilot, Perplexity, DeepSeek, Grok (xAI) and Meta AI.” In other words, using any browser-based AI assistant could expose sensitive conversations if these extensions are installed.

The mechanism is built directly into the extensions. Koi explains that “for each platform, the extension includes a dedicated ‘executor’ script designed to intercept and capture conversations.” This data harvesting is enabled by default through hardcoded settings, with no option for users to turn it off. As Koi warns, “There is no user-facing toggle to disable this. The only way to stop the data collection is to uninstall the extension entirely.”

Once installed, the extensions monitor browser activity. When a user visits a supported AI platform, the extension injects a specific script — such as chatgpt.js, claude.js, or gemini.js — into the page. The result is total visibility into AI usage. As Koi puts it, this includes “Every prompt you send to the AI. Every response you receive. Conversation identifiers and timestamps. Session metadata. The specific AI platform and model used.”

The main extension involved is Urban VPN Proxy, which alone has around six million users. After identifying its behavior, Koi searched for similar code and found it reused across multiple products from the same publisher, spanning both Chrome and Microsoft Edge.

Affected Chrome Web Store extensions include:

On Microsoft Edge Add-ons, the list includes:

Despite this activity, most of these extensions carry “Featured” badges from Google and Microsoft. These labels suggest that the tools have been reviewed and meet quality standards — a signal many users trust when deciding what to install.

Koi and other experts argue that this highlights a deeper problem with extension privacy disclosures. While Urban VPN does technically mention some of this data collection, it’s easy to miss. During setup, users are told the extension processes “ChatAI communication” along with “pages you visit” and “security signals,” supposedly “to provide these protections.”

Digging deeper, the privacy policy spells it out more clearly: “‘AI Inputs and Outputs. As part of the Browsing Data, we will collect the prompts and outputs queried by the End-User or generated by the AI chat provider, as applicable.’” It also states plainly: “‘We also disclose the AI prompts for marketing analytics purposes.’”

The extensions, Koi warns, “remained live for months while harvesting some of the most personal data users generate online.” The advice is blunt: “if you have any of these extensions installed, uninstall them now. Assume any AI conversations you've had since July 2025 have been captured and shared with third parties.”