WP Event Manager < 3.4.2 - Subscriber+ Arbitrary Post Takeover via event_organizer_ids

Description

The plugin does not properly validate ownership or the type of the user-supplied post identifiers processed by one of its frontend forms, allowing any user with a Subscriber account or above to reassign the authorship of arbitrary posts to themselves and to force them to be published. This results in content takeover and in the public disclosure of otherwise private or draft content, and requires the relevant frontend feature to be enabled.