This could allow a malicious actor to execute commands on the target website. This can be used to gain backdoor access to then take full control of the 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.
Update to version 4.2999 or later to remove the vulnerability. Patchstack users can turn on auto-update for vulnerable plugins only.