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Remediation Steps:
Perform following to update remove RDS instance master username public access :
Login to the AWS Management Console at https://console.aws.amazon.com as root user.
Navigate to VPC console.
On Navigation pane, choose Route Tables.
Click on the route table to be modified.
Under the route table description select Routes tab and click Edit Routes.
Remove any routes which provide public access and modify other routes accordingly.
Click on Save routes.
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