The Deep Hardware Link
Google Chrome features an incredibly advanced API designed to interface directly with physical Serial Ports (COM ports on Windows). This allows web-based applications to communicate directly with highly specialized hardware, such as 3D printers, micro-controllers (like Arduinos), and medical devices plugged into your USB ports. While this is a massive technological achievement, it is a terrifying security vulnerability for the average user. If a malicious website manages to hijack this API, it can theoretically execute raw commands against your physical, external hardware. You must completely lock out this access.
How to Block Serial Port Access Globally
You can permanently sever the browser’s connection to your physical COM ports via the Site Settings.
- Open the Google Chrome desktop browser.
- Click the three vertical dots (⋮) in the top right corner and select Settings.
- In the left-hand sidebar, click on Privacy and security.
- In the main window, click on Site settings.
- Scroll down to the bottom and click to expand Additional permissions.
- Click on Serial ports.
- Under the “Default behavior” heading, select the radio button for “Don’t allow sites to connect to serial ports.”
Hardware Lockdown
The change takes effect instantly. Google Chrome will completely sever its internal connection to the Windows or macOS serial driver registry. The browser will instantly auto-reject every single background request from any website attempting to scan your USB interfaces for connected hardware. You will never see a permission pop-up, and you can browse the internet with the absolute guarantee that your physical external devices are completely isolated from malicious web scripts.