The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.
The remote web server may have had malicious code injected.
The remote web server may have been infected with a malicious script tag. These tags usually point to a malicious site that is hosting code designed to subvert the security of the client machine.
Ensure that the server is not serving malicious or injected script tags.