This host is not managed by the Insured, or is hosted by a 3rd party. Is this vulnerability still valid?

While the Insured may not own or manage the server, these vulnerabilities affect their website and potentially their clients/visitors and should still be addressed. 

Even if it does not affect the Insured's internal system, a few concerns remain. They’ve permitted that service to communicate on their behalf, so if that service is compromised, there is a risk that the Insured's business would be affected. 

As the website is hosted by a 3rd party, the Insured will not be able to take direct remediation action themselves. Therefore, it’s recommended that they notify the hosting provider of the vulnerability and request that they follow the remediation steps presented in the Perimeter Report.