To fix windows security vulnerabilities, you need to scan your computer system first to find out the problems.

Start up WinMend System Doctor, click "Scan Settings" button in the main interface.

Select the option "Scan windows security vulnerabilities", click "save".

Click "diagnose" button to scan windows system vulnerabilities.

After scanning, you'll find the system vulnerabilities.

Click "repair" button to fix the security problems.

After windows security problems fixed, there's a reboot confirmation window pop-up. You can click "Yes" to reboot your computer for the updates to take effect, or click "No" for later.