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Remediation Steps:
Perform following to modify remove public sharing configuration from snapshots for Neptune :
Login to the AWS Management Console at https://console.aws.amazon.com.
Navigate to Neptune console.
In the navigation pane, click on Snapshots.
Select the snapshot that is shared.
Click Actions button, select Share snapshot option.
Under Preferences, select DB snapshot visibility as Private.
Check the Delete check box corresponding to the entry with AWS Account ID as all.
Click Save button.
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