The WP Event Manager WordPress plugin before 3.4.2 does not verify the ownership or the post type of a user supplied post identifier in its front-end event submission flow, allowing unauthenticated attackers to read and overwrite the content of arbitrary unpublished posts and pages, and to convert them into events.
https://wpscan.com/vulnerability/bcc4df7e-86a0-4614-9b3a-8629f6335b8a/