What is CVE-2021-43812?

CVE-2021-43812 is a medium-severity vulnerability in Auth0 Nextjs-Auth0, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.4/10. Published 2021-12-16.

How severe is CVE-2021-43812?

Medium severity. CVSS v3 base score is 6.4 out of 10.

Open Redirect in Auth0 Nextjs-Auth0

CVE-2021-43812

The Auth0 Next.js SDK is a library for implementing user authentication in Next.js applications. Versions before 1.6.2 do not filter out certain returnTo parameter values from the login url, which expose the application to an open redirect vulnerability. Users are advised to upgrade as soon as possible. There are no known workarounds for this issue.

Vulnerability class: Open Redirect

Published 2021-12-16 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.007 (49.4th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 49.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Auth0 Nextjs-Auth0 — versions < 1.6.2

Weakness classification (CWE)

CWE-601 — URL Redirection to Untrusted Site (Open Redirect)

References

github.com/auth0/nextjs-auth0/security/advisories/GHSA-2mqv-4j3r-vjvp (Third Party Advisory)
github.com/auth0/nextjs-auth0/commit/0bbd9f8a0c93af51f607f28633b5fb18c5e48ad6 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-43812?: CVE-2021-43812 is a medium-severity vulnerability in Auth0 Nextjs-Auth0, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.4/10. Published 2021-12-16.
How severe is CVE-2021-43812?: Medium severity. CVSS v3 base score is 6.4 out of 10.