Make your Mac ask before an unknown USB device connects

Why it happens

A USB stick or cable can carry more than files or power, and one you didn't buy could pretend to be a keyboard or try to read data. Mac laptops with Apple silicon can keep a new accessory out until you click Allow. Desktop Macs and Intel Macs don't have this setting, so being careful about what you plug in is the main protection there.

How to fix it

1. Open the Apple menu, choose System Settings, and click Privacy & Security in the sidebar.

2. Scroll down to Allow accessories to connect. On macOS 26 it's in the Security part; on macOS 27 it's under Accessories.

   macOS 26 Tahoe Privacy & Security›Allow accessories to connect

   macOS 27 Golden Gate Privacy & Security›Accessories›Allow accessories to connect

3. Choose Ask Every Time for the most care, or Ask for New Accessories to be asked only about things you haven't allowed before. You may need to enter your password.

4. From now on, when you plug something in, your Mac asks first. Click Allow only for things you know and trust; Don't Allow keeps it out.

On macOS 26 the setting sits in the Security part of Privacy & Security. On macOS 27 it's in the same pane under its own Accessories heading. The choices are the same.

Still not fixed?

1. Found a USB stick? Don't plug it in at all. Even if you allow it, it can hold harmful files. Hand it in instead.

2. At airports and hotels, plug your own power adapter into a wall socket rather than using a USB port, so the port can only give power.

3. Allowed something by mistake? Unplug it. Then look in Login Items & Extensions for anything new you didn't add.

   General›Login Items & Extensions

4. If your Mac acts strangely after you plug something in, like typing or opening apps on its own, unplug it, shut down, and contact Apple Support.