This could allow a malicious actor to get a website to load an external website or script which will then be executed on the website. This could allow the malicious actor to create backdoors on the site or 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 2.7.5 or later to remove the vulnerability. Patchstack users can turn on auto-update for vulnerable plugins only.