The ProSolution WP Client plugin for WordPress contains an unvalidated file upload function named proSol_fileUploadProcess that allows any file type to be stored on the server. This flaw, classified as CWE‑434, enables an attacker to upload executable or script files to a publicly accessible location, potentially leading to remote code execution, data compromise, or service disruption.

WordPress sites running ProSolution WP Client version 1.9.9 or earlier are affected. Any installation that has not been updated to a later release remains vulnerable.

The CVSS score of 9.8 signifies critical severity, and the vulnerability can be exploited without authentication by sending a crafted HTTP request to the upload endpoint. Although no EPSS score is available and the vulnerability is not listed in the CISA KEV catalog, the lack of authentication requirement and the nature of the flaw imply that exploitation is likely straightforward once the plugin is in place.