Yes—if the WU-1a is left on its default settings, the Wi‑Fi network may be unsecured, which could allow another nearby device to connect. The key protection is to configure the adapter to use a password-secured Wi‑Fi network rather than the default open network.

To prevent unauthorized access:

• Set up security on the WU-1a’s Wi‑Fi network.
• Configure the password both on the adapter/camera side and in the Wireless Mobile Utility device you use.
• Avoid using the default unsecured setup in public places.

The “only one camera can be connected at a time” note does not mean the connection is automatically private; it mainly describes app/device connection behavior, not security. If your connection drops and the network is open, another device could potentially join.

In short: secure the WU-1a with a password before using it in public.