Unrestricted upload of files with dangerous MIME types in the WP‑Advanced‑Search plugin allows an attacker to upload a web shell to the hosting server. The vulnerability permits execution of arbitrary code on the web server, compromising confidentiality, integrity, and availability of the site. The weakness is classified as CWE‑434, representing an arbitrary file upload flaw.

The WordPress WP‑Advanced‑Search plugin made by Mathieu Chartier, versions 3.3.9.4 and earlier, are affected. Sites using any older version of the plugin are vulnerable until the plugin is upgraded beyond 3.3.9.4.

The CVSS score is 6.6, indicating a moderate severity. The EPSS score is less than 1%, suggesting a low probability of exploitation in the wild, and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector is via the plugin’s web‑based file upload interface, which can be accessed remotely by an attacker with or without authentication, depending on the site’s configuration. Successful exploitation requires the attacker to successfully upload a web shell file that the server will execute when accessed.