CSRF Token Mismatch Across Multiple Pods in Node.js React Kubernetes Deployment

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I'm running a Node.js app with a React frontend that uses CSRF protection, and it works fine with a single instance. However, when I deploy multiple replicas in my Kubernetes cluster, I start getting an "Invalid CSRF" error. I verified that the CSRF token is correctly stored in the session table in the database.

Here's how I've implemented it:

JAVASCRIPT
// initial-csrf.js

var csrf = require("csurf");

const csrfProtection = csrf({});

module.exports = {
 csrfProtection,
};

// Server.js
app.use(csrfProtection); // It goes after app.use(appSession);

// Session controller

const csrfToken = (req, res) => {
 res.send(req.csrfToken());
};

// Initial express session

var appSession = session({
  store: new postgresSession({
    pool: sessionDBaccess,
    tableName: "sessions",
  }),
  name: "mCookie",
  secret: "my-secret"
  resave: false,
  saveUninitialized: false,
  cookie: {
    maxAge: 1000 * 60 * 60 * 24 * 7,
    sameSite: true,
    secure: false,
  },
});

In my React code, I send a request as follows:

JAVASCRIPT
handleCreate() {
  const csrf_data = {};

  const csrf_response = callAxios(
    "/api/sessions/csrfToken",
    "GET",
    csrf_data,
  );
  csrf_response.then((csrf_res) => {
    const data = {
      // some data
    };
    const response = callAxios("/api/sessions", "POST", data, csrf_res.data);
    response.then((res) => {
      if (res) {
        if (res.data) {
          // Some functions
        } else {
          if (res.response) {
            // Some functions
          }
        }
      }
    });
  });
}

I suspect this might be related to session consistency or cookie sharing across pods, but I'm not sure what could be causing the issue. Any ideas?

Comments 0

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 1 month ago

It sounds like you’re running into session consistency issues in your distributed environment. Although your sessions are stored in a common PostgreSQL store, the CSRF middleware depends on the session cookie that is returned with the CSRF token. When you scale horizontally you must make sure that:

The same session cookie is used on subsequent requests.
If clients do not send the exact same session cookie (for example if your axios requests are not sending credentials), then the POST request might hit a different pod that doesn’t have the expected session (or the session won’t match the earlier CSRF secret).
Session secret and configuration are identical across pods.
All pods must use the same session configuration (including the session secret “my-secret” and cookie settings) so that sessions are properly shared between instances.
Load balancer settings vs. sticky sessions / session affinity.
Even though you’re storing sessions in an external database, if cookies aren’t persisted properly then the CSRF token won’t match. You might either need to configure your load balancer to use sticky sessions or – more robustly – ensure your client (axios) is configured to send and keep cookies on every request.

For example, in axios make sure you have something like:

JAVASCRIPT
axios.defaults.withCredentials = true;

Or in your individual call:

JAVASCRIPT
callAxios(url, method, data, token) {
  return axios({
    url,
    method,
    data,
    headers: {
      'CSRF-Token': token // or whichever header your server expects
    },
    withCredentials: true // ensures the cookie is included with the request
  });
}

Double-check that:

The domain/path for your session cookie is set correctly so that all requests (regardless of the instance it lands on) include the same cookie.
Your frontend is sending requests with credentials enabled. Without this, your GET for “/api/sessions/csrfToken” might work, but the following POST won’t associate with the same session.
The session middleware is configured correctly across all replicas (same secret, cookie options, etc.).

These steps should alleviate the CSRF invalid error caused by sessions not being maintained properly across multiple pods.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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CSRF Token Mismatch Across Multiple Pods in Node.js React Kubernetes Deployment

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