How severe is CVE-2021-43812?

CVE-2021-43812 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-43812?

CVE-2021-43812 affects the following packages: @auth0/nextjs-auth0 (npm). Ecosystems affected: npm.

How do I fix CVE-2021-43812?

Update @auth0/nextjs-auth0 to 1.6.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43812 is resolved across your whole dependency graph.

How do I detect CVE-2021-43812 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @auth0/nextjs-auth0, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-43812 if there is no patch (or I can't update yet)?

Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Is CVE-2021-43812 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-43812 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-43812?

CVE-2021-43812 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 52th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-43812?

CVE-2021-43812 is classified as Open Redirect (CWE-601). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-43812 published, and has it been updated?

CVE-2021-43812 was published on December 16, 2021 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

CVE-2021-43812 — @auth0/nextjs-auth0

MEDIUMFix: auth0/nextjs-auth0@0bbd9f8

CVE-2021-43812 is a medium-severity (CVSS 6.1) Open Redirect vulnerability in @auth0/nextjs-auth0. A fix is available for @auth0/nextjs-auth0 — see the affected versions and patch details below.

Open redirect in @auth0/nextjs-auth0

Also known asGHSA-2mqv-4j3r-vjvp

Published

Dec 16, 2021

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs52th percentile — riskier than 52% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

41other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@auth0/nextjs-auth0npm

1.3Mdownloads / week

Description

Overview

Versions <=1.6.1 do not filter out certain returnTo parameter values from the login url, which expose the application to an open redirect vulnerability.

Am I affected?

You are affected by this vulnerability if you are using @auth0/nextjs-auth0 version <=1.6.1.

How to fix that?

Upgrade to version >=1.6.2

Will this update impact my users?

The fix provided in the patch will not affect your users.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@auth0/nextjs-auth0`	all versions	1.6.2`npm install @auth0/nextjs-auth0@1.6.2`

Affected Products

1 product · 1 configurations

Application

nextjs-auth0auth0

< 1.6.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @auth0/nextjs-auth0, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @auth0/nextjs-auth0 to 1.6.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43812 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Frequently Asked Questions

### Overview Versions `<=1.6.1` do not filter out certain `returnTo` parameter values from the login url, which expose the application to an open redirect vulnerability. ### Am I affected? You are affected by this vulnerability if you are using `@auth0/nextjs-auth0` version `<=1.6.1`. ### How to fix that? Upgrade to version `>=1.6.2` ### Will this update impact my users? The fix provided in the patch will not affect your users.

O3 Security · Impact-Aware SCA

Is CVE-2021-43812 in your dependencies?

Find it across npm, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

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

CWE Classification

CWE-601Open Redirect

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

OpenSSF Scorecard

Package health score

nextjs-auth0

7.1/10

Maintained10/10

Code-Review10/10

Branch-Protection5/10

Assessed Nov 2, 2026

Timeline

Disclosed

Dec 16, 2021

Last updated

Oct 20, 2026

Identifiers

CVE-2021-43812

GHSA-2mqv-4j3r-vjvp

References

Advisorygithub.com · GHSA 2mqv 4j3r vjvp Advisorynvd.nist.gov · CVE 2021 43812 Fixgithub.com · 0bbd9f8a0c93af51f607f28633b5fb18c5e48ad6 Packagegithub.com · nextjs auth0

Related vulnerabilities

Also affects @auth0/nextjs-auth0

This CVE is medium severity; 5 of 6 other CVEs affecting @auth0/nextjs-auth0 are rated as high or higher (top: high).

CVE-2026-40155CVE-2025-67716CVE-2025-67490CVE-2025-48947CVE-2025-46344CVE-2021-32702

Same weakness: CWE-601

This CVE is medium severity; 1 of 2 other CVEs with CWE-601 is rated as high or higher (top: moderate).

CVE-2026-118658CVE-2026-116578Browse all CWE-601

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026