Formidable Forms 6.34 - Unauthenticated Stored Content Injection via 'updated_by' Parameter

The Formidable Forms WordPress plugin before 6.35 does not restrict who can set the identifier recording which user last edited a form entry, and relies on that identifier when deciding whether to strip HTML from stored entry values, allowing unauthenticated visitors to have markup rendered in the admin entry view that would otherwise be removed, and to attribute their submission to an administrator who never made it.