cgi.js forwards a CGI request to a server. It works with both http.Server and Express (if using http.Server as well). Performance is lacking as there is a lot of overhead from CGI.

.htaccess

Options +ExecCGI
AddHandler cgi-script cgi

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule (.*) server.cgi

cgi.js

const net = require('net');
const http = require('http');
const path = require('path');

module.exports = function cgi (server, port, cb) {
  let env = process.env;
  if( !env['DOCUMENT_ROOT'] ) {
    server.listen(port, cb);
  } else {
    let data = '';
    process.stdin.on('data', function(chunk){
      data += chunk;
    });
    process.stdin.on('end', function(){
      server.listen(0, function(){
        let method = env['REQUEST_METHOD'] || 'GET';
        let uri = path.join(env['DOCUMENT_ROOT'], env['REQUEST_URI']).replace(__dirname, '');

        let opts = {
          method: method,
          path: uri,
          hostname: '127.0.0.1',
          port: server.address().port,
          headers:{}
        };

        for( let key in env ) {
          if( /^http_/i.test(key) ) {
            opts.headers[key.replace(/^http_/i, '').replace(/_/g, '-')] = env[key];
          }
        }

        opts.headers['Content-Length'] = Buffer.byteLength(data);

        let rawHttp = new Buffer('');
        let con = http.request(opts, function(res){
          res.on('data', function(chunk){
          }).on('end', function(){
            let str = rawHttp.toString();
            str = str.replace(/^HTTP(S?)\/\d\.\d (.+)$/m, 'Status: $2');
            server.close();
          });
        }).on('socket', function(socket){
          socket.on('data', function(chunk){
            rawHttp += chunk;
          });
        }).on('error', function(err){
          console.log('ERROR CGI', err);
        });

        con.on('close', function(){
          server.close();
        });

        con.write(data+'\r\n');
        con.end();

      });
    });
  }
}

server.cgi

#!/bin/env node
require('./server.js');

server.js

#!/bin/env node
const http = require('http');
const express = require('express');
const cgi = require('./cgi');

const PORT = process.env['PORT'] || 3000;
const DOCUMENT_ROOT = process.env['DOCUMENT_ROOT'] || process.env['NODE_ROOT'];

let app = express();
let server = http.createServer(app);

app.get('*', (req, res)=>{
  res.send('Hello World');
});

cgi(server, PORT);