Open Redirect in Feathersjs with Jwt Tokens

An Open Redirect in a Feathersjs application that uses Jwt Tokens occurs when an attacker can influence the redirect target after authentication, typically through a URL parameter that is not properly validated. Because Feathersjs applications often issue Jwt Tokens after login and then redirect the client to a configured URI (e.g., a dashboard or return URL), an unchecked redirect parameter can lead to token disclosure or session fixation in the browser.

Consider a login route that accepts a redirect query parameter and, upon successful Jwt Token generation, redirects the user without validating the destination. An example vulnerable implementation might look like this:

// WARNING: vulnerable example — do not use in production
app.service('authentication').hooks({
  before: {
    create: [context => {
      const redirectTo = context.data.redirect || '/dashboard';
      // ... validate credentials and issue Jwt Token ...
      context.result = { token, redirect: redirectTo };
    }]
  }
});

In this scenario, the redirect value is taken directly from user input. If an attacker crafts a login link such as https://api.example.com/authentication?redirect=https://evil.com, the server may issue a Jwt Token and then instruct the client to navigate to the attacker-controlled site. This can facilitate phishing, as the user may be redirected after login with a valid Jwt Token in a fragment or query parameter that is unintentionally exposed.

When using Jwt Tokens, the risk is compounded if the token is passed in the URL (e.g., as a query parameter or fragment) during the redirect. Tokens in URLs can be leaked in browser history, server logs, or referrer headers. Feathersjs does not inherently protect against open redirects; it is the developer’s responsibility to validate and restrict redirect targets to a whitelist of trusted paths or origins. Without such controls, the combination of Jwt Tokens and open redirects creates a pathway for token leakage and unauthorized redirection to malicious sites.

Additionally, if your Feathersjs API serves both API and web views, ensure that redirects are only allowed to same-origin routes or explicitly permitted domains. Attackers may abuse OAuth-like flows where the redirect URI is dynamically set, leading to token exfiltration or session hijacking when Jwt Tokens are used for downstream API calls.

To remediate Open Redirect when using Jwt Tokens in Feathersjs, enforce strict allowlists for redirect targets and avoid including tokens in URLs. Below are concrete code examples that demonstrate a secure approach.

1. Validate redirect against a whitelist

Instead of using arbitrary user-supplied URLs, restrict redirects to known, safe paths. This prevents open redirects and reduces the chance of Jwt Token leakage via referrer headers.

const allowedOrigins = ['https://app.example.com', 'https://app.example.com/dashboard', '/dashboard', '/profile'];

app.service('authentication').hooks({
  before: {
    create: [context => {
      const redirectTo = context.data.redirect;
      let target = '/dashboard';

      if (redirectTo) {
        const isSameOrigin = allowedOrigins.some(origin =>
          origin === redirectTo || (origin.startsWith('http') && new URL(redirectTo, origin).origin === origin)
        );
        if (isSameOrigin) {
          target = redirectTo;
        }
      }

      // Issue Jwt Token (example using jsonwebtoken)
      const token = jwt.sign({ sub: context.result.user.id }, process.env.JWT_SECRET, { expiresIn: '1h' });
      context.result = { token, redirect: target };
    }]
  }
});

2. Avoid passing Jwt Tokens in URLs

Return the Jwt Token in the response body or an HttpOnly cookie instead of embedding it in a redirect URL. If you must include it in a fragment for client-side routing, ensure the redirect is strictly validated and the token is not exposed in logs or referrers.

app.service('authentication').hooks({
  before: {
    create: [async context => {
      // Validate credentials and produce Jwt Token
      const token = jwt.sign({ sub: context.result.user.id }, process.env.JWT_SECRET, { expiresIn: '1h' });

      // Safe response: token in body, redirect to a validated destination
      const redirectTo = '/dashboard'; // default
      context.result = {
        token,
        redirect: redirectTo
      };
    }]
  }
});

3. Server-side redirects with no open exposure

If you perform server-side redirects, ensure the Location header is constructed from a trusted origin and never reflects untrusted input directly.

// Example for an Express-style integration within Feathersjs hooks
app.hooks({
  after: {
    create: [context => {
      const redirectTo = '/dashboard'; // hardcoded or from config
      if (context.result && context.result.redirect) {
        // Ensure redirectTo is safe before setting header
        context.headers.location = redirectTo;
      }
      return context;
    }]
  }
});

These measures align with secure handling of Jwt Tokens by preventing open redirects and minimizing token exposure in URLs. Combined with framework-agnostic best practices such as using HttpOnly cookies for token storage and strict referrer policies, they help maintain the integrity of authentication flows in Feathersjs applications.