As immediate action, update the affected plugin. If you're unable to do so, ask your hosting provider or web developer for help.
Attackers can run any command on the server from anywhere in the world.
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.
Update to version 3.1.1 or later to resolve the vulnerability.
This software was last updated over a year ago and will likely not receive further updates or patches. Note that deactivating the software does not remove the security threat unless mitigation rule by Patchstack is deployed.