Modern Events Calendar lite <= 5.16.2 - Admin+ Stored XSS

The plugin does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).

PoC

1. Go to the import/export section. 2. Enter the following payload in the input fields of Google API key and Calendar ID: ">