The Modern Event Calendar Pro WordPress plugin before 7.34.0, Modern Events Calendar Lite WordPress plugin before 7.34.0 do not sanitise and escape a request parameter before using it in a SQL statement, through an AJAX action available to unauthenticated users, leading to an unauthenticated SQL injection vulnerability that allows attackers to extract sensitive data from the database.

The Modern Events Calendar Lite plugin for WordPress is vulnerable to SQL Injection via the 'id' parameter of the 'wpajaxmecloadsinglepage' AJAX action in all versions up to, and including, 6.3.0 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for unauthenticated attackers to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database. This is only exploitable on sites with addslashes disabled.

The Modern Events Calendar Lite plugin for WordPress is vulnerable to Full Path Disclosure in all versions up to, and including, 7.21.9. This is due improper or insufficient validation of the id property when exporting calendars. This makes it possible for unauthenticated attackers to retrieve the full path of the web application, which can be used to aid other attacks. The information displayed is not useful on its own, and requires another vulnerability to be present for damage to an affected website.

The Modern Events Calendar plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 7.12.1 via the 'mecfesform' AJAX function. This makes it possible for authenticated attackers, with Subscriber-level access and above, to make web requests to arbitrary locations originating from the web application and can be used to query and modify information from internal services.