Client.prototype.unforwardIn = function(bindAddr, bindPort, cb) {
  if (!this._sock
      || !this._sock.writable
      || !this._sshstream
      || !this._sshstream.writable)
    throw new Error('Not connected');

  // send a request to stop forwarding us new connections for a particular
  // address and port

  var self = this;
  var wantReply = (typeof cb === 'function');

  if (wantReply) {
    this._callbacks.push(function(had_err) {
      if (had_err) {
        return cb(had_err !== true
                  ? had_err
                  : new Error('Unable to unbind from '
                              + bindAddr + ':' + bindPort));
      }

      delete self._forwarding[bindAddr + ':' + bindPort];

      cb();
    });
  }

  return this._sshstream.cancelTcpipForward(bindAddr, bindPort, wantReply);
};
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.