Reflected XSS vulnerability in Auth0 Next.js SDK (<=1.4.1) allows arbitrary code execution

CVE-2021-32702 · MEDIUM Severity

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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.

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