Description
The Auth0 Next.js SDK is a library for implementing user authentication in Next.js applications. Versions 4.9.0 through 4.12.1 contain an input-validation flaw in the returnTo parameter, which 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. This issue is fixed in version 4.13.0.
Affected products
auth0: nextjs-auth0
References2
Metrics
- CVSS 3.1
-
5.7
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N - EPSS — exploit probability
- 0% percentile: 20 · as of 11 November 2026
- CWE
- CWE-184
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.