Add User Meta plugin is missing or incorrectly validating nonces on the add‑user‑meta page. This allows an attacker who can persuade an administrator to visit a crafted URL to submit a forged request. The forged request updates plugin settings and stores malicious JavaScript code that will be executed whenever the affected page is viewed, leading to stored cross‑site scripting. Because the injected script runs in the context of the site administrator, it can read cookies, hijack sessions, or redirect users, compromising confidentiality, integrity, and availability of the administrative interface.

The vulnerability affects all installations of the Add User Meta WordPress plugin version 1.0.1 and earlier. The plugin is distributed by the author Joshua Lau and available on the official WordPress plugin repository. Sites that have not upgraded beyond 1.0.1 remain susceptible. Since the vulnerability is tied to the plugin’s admin interface, any WordPress site that relies on this plugin for handling user metadata triggers the risk.

The CVSS base score is 6.1, signifying moderate severity. The EPSS score is below 1%, indicating a low probability of exploitation at present. The vulnerability is not listed in the CISA KEV catalog. The likely attack vector involves a CSRF exploit, where the attacker relies on an authenticated administrator to perform an unintended action after clicking a malicious link. Once the forged request executes, the stored XSS payload can persist until the plugin settings are changed or the plugin is removed. Given the moderate score but low EPSS, administrators should consider patching promptly but can monitor for phishing attempts.