Jetpack Protect extension allows you to see any vulnerabilities on your child sites directly in your MainWP Dashboard.
The extension works in tandem with the Jetpack Protect plugin on your child sites. Both the extension and the plugin are free to download and use.
NOTE: Jetpack Protect automatically scans your child sites once per day. This means that after resolving vulnerability issues, it can take up to 24 hours before the extension reflects changes.