_dbus_header_delete_field (DBusHeader *header,
                           int         field)
{
  DBusTypeReader reader;
  DBusTypeReader realign_root;

  if (_dbus_header_cache_known_nonexistent (header, field))
    return TRUE; /* nothing to do */

  /* Scan to the field we want, delete and realign, reappend
   * padding. Field may turn out not to exist.
   */
  if (!find_field_for_modification (header, field,
                                    &reader, &realign_root))
    return TRUE; /* nothing to do */

  if (!reserve_header_padding (header))
    return FALSE;

  if (!_dbus_type_reader_delete (&reader,
                                 &realign_root))
    return FALSE;

  correct_header_padding (header);

  _dbus_header_cache_invalidate_all (header);

  _dbus_assert (!_dbus_header_cache_check (header, field)); /* Expensive assertion ... */

  return TRUE;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.