Improper Validation of Query Parameters in Auth0 Next.js SDK

### Description An input-validation flaw in the returnTo parameter in the Auth0 Next.js SDK could allow attackers to inject unintended OAuth query parameters into the Auth0 authorization request. Successful exploitation may result in tokens being issued with unintended parameters ### Am I Affected? You are affected if you meet the following preconditions: - Applications using the auth0/nextjs-auth0 SDK version prior to 4.13.0 ### Affected product and versions Auth0/nextjs-auth0 versions >= 4.9.0 and < 4.13.0 ### Resolution Upgrade Auth0/nextjs-auth0 version to v4.13.0 ### Acknowledgements Okta would like to thank Joshua Rogers (MegaManSec) for their discovery and responsible disclosure.

Source published

10 Dec 2025 21:35:58 UTC

Source modified

11 Dec 2025 16:21:52 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N

Publisher rating · LOW