CVE-2021-32702: AUTH0 Nextjs-AUTH0

Medium severity, CVSS 6.1. EPSS: 1.4% chance of exploitation in the next 30 days.

The Auth0 Next.js SDK is a library for implementing user authentication in Next.js applications. Versions before and including `1.4.1` are vulnerable to reflected XSS. An attacker can execute arbitrary code by providing an XSS payload in the `error` query parameter which is then processed by the callback handler as an error message. You are affected by this vulnerability if you are using `@auth0/nextjs-auth0` version `1.4.1` or lower **unless** you are using custom error handling that does not return the error message in an HTML response. Upgrade to version `1.4.1` to resolve. The fix adds basic HTML escaping to the error message and it should not impact your users.

Affected products

• AUTH0 Nextjs-AUTH0: before 1.4.2 (fixed in 1.4.2)

Published 2021-06-25. Last modified 2026-06-17.