Calendar Event Multi View < 1.4.07 - Unauthenticated Arbitrary Event Creation to Stored XSS

The plugin does not have any authorisation and CSRF checks in place when creating an event, and is also lacking sanitisation as well as escaping in some of the event fields. This could allow unauthenticated attackers to create arbitrary events and put Cross-Site Scripting payloads in it.

PoC

As an unauthenticated user, to add a malicious event (on October 6th, 2022) to the calendar with ID 1, open the code below The XSS will be triggered when viewing the related event