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.
This could allow a malicious actor to upload any type of file to your website. This can include backdoors which are then executed to gain further access to your website.
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.