The vulnerability exists in the Ad Inserter WordPress plugin in versions 2.8.12 through 2.8.18. It fails to enforce proper access control on a settings page, allowing any logged‑in user—including those with the Subscriber role—to store arbitrary PHP code. Because the plugin does not filter this input, the code is executed on the server, giving an attacker full control over the web application, and when rendered without escaping it also enables stored Cross‑Site Scripting for site visitors.

Sites running the Ad Inserter WordPress plugin, specifically versions 2.8.12 to 2.8.18, are affected.

The CVSS score of 7.5 indicates high severity, and the EPSS score is < 1%, indicating a very low but non‑zero exploitation probability. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires authentication with a Subscriber role. Once a subscriber uploads malicious code, it runs with the web server’s privileges, leading to a complete site compromise, while the stored XSS component can be used for phishing or credential theft against site visitors.