  authPasswdChg(prompt) {
    if (!this._server)
      throw new Error('Server-only method called in client mode');

    const promptLen = Buffer.byteLength(prompt);
    let p = this._packetRW.write.allocStart;
    const packet = this._packetRW.write.alloc(1 + 4 + promptLen + 4);

    packet[p] = MESSAGE.USERAUTH_PASSWD_CHANGEREQ;

    writeUInt32BE(packet, promptLen, ++p);
    packet.utf8Write(prompt, p += 4, promptLen);

    writeUInt32BE(packet, 0, p += promptLen); // Empty language tag

    this._debug && this._debug('Outbound: Sending USERAUTH_PASSWD_CHANGEREQ');
    sendPacket(this, this._packetRW.write.finalize(packet));
  }
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.