OpenCATS is an open-source applicant tracking system and recruitment CRM for staffing agencies and hiring teams. Prior to version 0.10.0, the Professional License configuration feature in "SettingsUI" ("manageProfessional") accepts administrator-controlled license key input that is reconstructed into a PHP "define()" statement in "config.php" without safe escaping. Because the application includes "config.php", crafted input can alter the file's PHP syntax and cause persistent arbitrary PHP execution with the web server process privileges. An authenticated administrator must have Settings module access and permission to update Professional License configuration, and "config.php" must be writable for this write-based path. Successful exploitation can read, modify or delete application data, expose candidate, contact, company, job order and user account information, alter the installation or configuration, and provide a foothold for further attacks. Unauthenticated exploitation and exploitation without Settings access are not established. This issue is fixed in version 0.10.0.