function permissions_load_cluster(cluster_name, callback) {
  var element_id = "permissions_cluster_" + cluster_name;
  ajax_wrapper({
    type: "GET",
    url: "/permissions_cluster_form/" + cluster_name,
    timeout: pcs_timeout,
    success: function(data) {
      $("#" + element_id).html(data);
      $("#" + element_id + " :checkbox").each(function(key, checkbox) {
        permissions_fix_dependent_checkboxes(checkbox);
      });
      permissions_cluster_dirty_flag(cluster_name, false);
      if (callback) {
        callback();
      }
    },
    error: function(xhr, status, error) {
      $("#" + element_id).html(
        "Error loading permissions " + ajax_simple_error(xhr, status, error)
      );
      if (callback) {
        callback();
      }
    }
  });
}
Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.