The Eventin – Event Manager, Events Calendar, Event Tickets and Registrations plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the 'post_settings' function in all versions up to, and including, 4.0.51. This makes it possible for unauthenticated attackers to modify plugin settings. Furthermore, due to insufficient input sanitization and output escaping on the 'etn_primary_color' setting, this enables unauthenticated attackers to inject arbitrary web scripts that will execute whenever a user accesses a page where Eventin styles are loaded.