This could allow a malicious actor to hijack a session of a higher privileged user. Once the session is hijacked, the malicious actor can gain 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 3.14 or later to remove the vulnerability. Patchstack users can turn on auto-update for vulnerable plugins only.