Client.prototype.rekey = function(cb) {
  var stream = this._sshstream;
  var ret = true;
  var error;

  try {
    ret = stream.rekey();
  } catch (ex) {
    error = ex;
  }

  // TODO: re-throw error if no callback?

  if (typeof cb === 'function') {
    if (error) {
      process.nextTick(function() {
        cb(error);
      });
    } else
      this.once('rekey', cb);
  }

  return ret;
};
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.