Direct static code injection is a vulnerability which could allow a malicious actor to inject machine or script code which is directly executed by the target website. This could allow a malicious actor to create a backdoor and 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 2.5.4 or later to remove the vulnerability. Patchstack users can turn on auto-update for vulnerable plugins only.