This vulnerability is highly dangerous and expected to become exploited. Vulnerabilities like this one are used in mass-exploit campaigns. Attackers use these to attack thousands of websites at a time, regardless of traffic size or popularity. Learn more.
As immediate action, update the affected plugin. If you're unable to do so, ask your hosting provider or web developer for help.
CVSS score is a way to evaluate and rank reported vulnerabilities in a standardized and repeatable way but which is not ideal for WordPress.
This security issue has a low severity impact and is unlikely to be exploited.