URL Redirection to Untrusted Site ('Open Redirect') in next-auth

Impact

We found that this vulnerability is present when the developer is implementing an OAuth 1 provider (by extension, it means Twitter, which is the only built-in provider using OAuth 1), but upgrading isstill recommended.

next-auth v3 users before version 3.29.3 are impacted. (We recommend upgrading to v4, as v3 is considered unmaintained. See our migration guide)

next-auth v4 users before version 4.3.3 are impacted.

Patches

We’ve released patches for this vulnerability in:

• v3 - 3.29.3
• v4 - 4.3.3

You can do:

npm i next-auth@latest

or

yarn add next-auth@latest

or

pnpm add next-auth@latest

(This will update to the latest v4 version, but you can change latest to 3 if you want to stay on v3.)

Workarounds

If you are not able to upgrade for any reason, you can add the following configuration to your callbacks option:

// async redirect(url, baseUrl) { // v3
async redirect({ url, baseUrl }) { // v4
    // Allows relative callback URLs
    if (url.startsWith("/")) return `${baseUrl}${url}`
    // Allows callback URLs on the same origin
    else if (new URL(url).origin === baseUrl) return url
    return baseUrl
}

References

This vulnerability was discovered right after https://github.com/nextauthjs/next-auth/security/advisories/GHSA-f9wg-5f46-cjmw was published and is very similar in nature.

Read more about the callbacks.redirect option in the documentation: https://next-auth.js.org/configuration/callbacks#redirect-callback

For more information

If you have any concerns, we request responsible disclosure, outlined here: https://next-auth.js.org/security#reporting-a-vulnerability

Timeline

The issue was reported 2022 April 20th, a response was sent out to the reporter 8 minutes after, and a patch was produced within a few days.