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 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.

The Modern Events Calendar plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the setfeaturedimage function in all versions up to, and including, 7.11.0. This makes it possible for authenticated attackers, with subscriber access and above, to upload arbitrary files on the affected site's server which may make remote code execution possible. The plugin allows administrators (via its settings) to extend the ability to submit events to unauthenticated users, which would allow unauthenticated attackers to exploit this vulnerability.

The Modern Events Calendar lite plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Google API key and Calendar ID in versions up to, but not including, 7.1.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfilteredhtml has been disabled.

Authenticated (admin+ user) Stored Cross-Site Scripting (XSS) in Modern Events Calendar Lite (WordPress plugin) <= 6.5.1

Unvalidated input in the Modern Events Calendar Lite WordPress plugin, versions before 5.16.6, did not sanitise the mec[postid] POST parameter in the mecfesform AJAX action when logged in as an author+, leading to an authenticated SQL Injection issue.

Arbitrary file upload in the Modern Events Calendar Lite WordPress plugin, versions before 5.16.5, did not properly check the imported file, allowing PHP ones to be uploaded by administrator by using the 'text/csv' content-type in the request.

Lack of authorisation checks in the Modern Events Calendar Lite WordPress plugin, versions before 5.16.5, did not properly restrict access to the export files, allowing unauthenticated users to exports all events data in CSV or XML format for example.

Unvalidated input and lack of output encoding in the Modern Events Calendar Lite WordPress plugin, versions before 5.16.5, did not sanitise the miccomment field (Notes on time) when adding/editing an event, allowing users with privilege as low as author to add events with a Cross-Site Scripting payload in them, which will be triggered in the frontend when viewing the event.

Multiple Stored Cross-site scripting (XSS) vulnerabilities in the Webnus Modern Events Calendar Lite plugin through 5.1.6 for WordPress allows remote authenticated users (with minimal permissions) to inject arbitrary JavaScript, HTML, or CSS via Ajax actions. This affects mecsavenotifications and importsettings.