Program: 11925
Project: 11925
Buggy source:
@Override public void handleReceived(ClientConnection connection){
  byte[] sharedSecret=null;
  byte[] token=null;
  try {
    sharedSecret=RSA.decrypt(this.encryptedSecret,connection.getLoginKeyPair().getPrivate());
    token=RSA.decrypt(this.encryptedToken,connection.getLoginKeyPair().getPrivate());
  }
 catch (  Exception e) {
    e.printStackTrace();
  }
  if (!Arrays.equals(connection.getVerificationToken(),token)) {
    System.out.println("String_Node_Str" + connection.getAddress().getHostName() + "String_Node_Str");
    connection.logout();
    return;
  }
  String name=LoginManager.getInstance().getName(connection.getAddress());
  StringBuilder sb=new StringBuilder();
  try {
    URL url=new URL("String_Node_Str" + URLEncoder.encode(name,"String_Node_Str") + "String_Node_Str"+ new BigInteger(HashGenerator.getHash(connection,sharedSecret)).toString(16));
    HttpsURLConnection c=(HttpsURLConnection)url.openConnection();
    int code=c.getResponseCode();
    if (code != 200) {
      connection.sendPacket(new PacketLoginOutDisconnect().setJsonMessage("String_Node_Str"));
      connection.logout();
      return;
    }
    BufferedReader reader=new BufferedReader(new InputStreamReader(c.getInputStream()));
    String line;
    while ((line=reader.readLine()) != null) {
      sb.append(line);
      sb.append('\n');
    }
    reader.close();
  }
 catch (  Exception ex) {
    ex.printStackTrace();
    connection.logout();
    return;
  }
  connection.enableEncryption(sharedSecret);
  SessionResponse response=GSON.fromJson(sb.toString(),SessionResponse.class);
  PacketLoginOutSuccess packet=new PacketLoginOutSuccess();
  packet.set("String_Node_Str",idDash.matcher(response.id).replaceAll("String_Node_Str"));
  packet.set("String_Node_Str",response.name);
  connection.sendPacket(packet);
  connection.setStage(Protocol.ClientStage.PLAY);
  UUID id=UUID.fromString(packet.getUuid());
  LoginManager.getInstance().finish(connection.getAddress());
  TridentPlayer.spawnPlayer(connection,id);
}

Fixed version (ground truth):
@Override public void handleReceived(ClientConnection connection){
  byte[] sharedSecret=null;
  byte[] token=null;
  try {
    sharedSecret=RSA.decrypt(this.encryptedSecret,connection.getLoginKeyPair().getPrivate());
    token=RSA.decrypt(this.encryptedToken,connection.getLoginKeyPair().getPrivate());
  }
 catch (  Exception e) {
    e.printStackTrace();
  }
  if (!Arrays.equals(connection.getVerificationToken(),token)) {
    System.out.println("String_Node_Str" + connection.getAddress().getHostName() + "String_Node_Str");
    connection.logout();
    return;
  }
  String name=LoginManager.getInstance().getName(connection.getAddress());
  StringBuilder sb=new StringBuilder();
  try {
    URL url=new URL("String_Node_Str" + URLEncoder.encode(name,"String_Node_Str") + "String_Node_Str"+ new BigInteger(HashGenerator.getHash(connection,sharedSecret)).toString(16));
    HttpsURLConnection c=(HttpsURLConnection)url.openConnection();
    int code=c.getResponseCode();
    if (code != 200) {
      connection.sendPacket(new PacketLoginOutDisconnect().setJsonMessage("String_Node_Str"));
      connection.logout();
      return;
    }
    BufferedReader reader=new BufferedReader(new InputStreamReader(c.getInputStream()));
    String line;
    while ((line=reader.readLine()) != null) {
      sb.append(line);
      sb.append('\n');
    }
    reader.close();
  }
 catch (  Exception ex) {
    ex.printStackTrace();
    connection.logout();
    return;
  }
  connection.enableEncryption(sharedSecret);
  SessionResponse response=GSON.fromJson(sb.toString(),SessionResponse.class);
  PacketLoginOutSuccess packet=new PacketLoginOutSuccess();
  packet.set("String_Node_Str",idDash.matcher(response.id).replaceAll("String_Node_Str"));
  packet.set("String_Node_Str",response.name);
  connection.sendPacket(packet);
  connection.setStage(Protocol.ClientStage.PLAY);
  UUID id=UUID.fromString(packet.getUuid());
  LoginManager.getInstance().finish(connection.getAddress());
  TridentPlayer.spawnPlayer(connection,id,name);
}