[Plugin: CKEditor For WordPress] How to stop occasional img-wrapping?

When I save a page or post, CKEditor occasionally wraps <img> in a <p>. On a Drupal forum, I read that

The reason the editors wrap tags is that they’re inline elements which must be contained by a block type element and are not allowed directly below the body element.

While this statement is wrong on several points – In my case, the <img> are child to a <div>.

Is this behavior documented? How can I prevent it?