This vulnerability is highly dangerous and expected to become exploited.
This could allow a malicious actor to include local files of the target website and show its output onto the screen. Files which store credentials, such as database credentials, could potentially allow complete database takeover depending on the configuration.
CVSS score is a way to evaluate and rank reported vulnerabilities in a standardized and repeatable way but which is not ideal for WordPress.
We advise to mitigate or resolve the vulnerability immediately.
Patchstack has issued a mitigation rule to block any attacks until you have updated to a fixed version.
Update to version 5.4.02 or later to remove the vulnerability. Patchstack users can turn on auto-update for vulnerable plugins only.
19 Mar, 2025