The Events Calendar Pro plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 7.0.2 via deserialization of untrusted input from the 'filters' parameter in widgets. This makes it possible for authenticated attackers, with administrator-level access and above, to inject a PHP Object. The additional presence of a POP chain allows attackers to execute code remotely. In certain configurations, this can be exploitable by lower level users. We confirmed that this plugin installed with Elementor makes it possible for users with contributor-level access and above to exploit this issue.