Cleans all given post_type of CDATA sections

content_fix.php

// Clean CDATA in database
add_action('init', 'clean_posts');
function clean_posts() {
  /* Run on the following post_types post, page, attachment and wpcf7_contact_form */
  $content_posts = get_posts( array('post_type' => 'post', 'numberposts' => -1) );
  $str = array('<!--[CDATA[', '<![CDATA[', '-->', ']]>', '<![CDATA[]]>');
  foreach ( $content_posts as $content_post ) {
    $old_content = $content_post->post_content;
    $content_post->post_content = str_replace($str, '', $old_content);
    wp_update_post( $content_post );
  }
}