CVE-2021-37699 — next
MEDIUMCVE-2021-37699 is a medium-severity (CVSS 6.1) Open Redirect vulnerability in next. A fix is available for next — see the affected versions and patch details below.
Open Redirect in Next.js
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-37699 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 386,684 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
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.
nextnpmDescription
Next.js is an open source website development framework to be used with the React library. In affected versions specially encoded paths could be used when pages/_error.js was statically generated, allowing an open redirect to occur to an external site. In general, this redirect does not directly harm users although it can allow for phishing attacks by redirecting to an attacker's domain from a trusted domain.
Impact
- Affected: Users of Next.js between
10.0.5and10.2.0 - Affected: Users of Next.js between
11.0.0and11.0.1usingpages/_error.jswithoutgetInitialProps - Affected: Users of Next.js between
11.0.0and11.0.1usingpages/_error.jsandnext export - Not affected: Deployments on Vercel (vercel.com) are not affected
- Not affected: Deployments with
pages/404.js - Note that versions prior to 0.9.9 package
nextnpm package hosted a different utility (0.4.1 being the latest version of that codebase), and this advisory does not apply to those versions.
We recommend upgrading to the latest version of Next.js to improve the overall security of your application.
Patches
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | next | ≥ 0.9.9&&< 11.1.0 | 11.1.0npm install next@11.1.0 |
Affected Products
next.jsvercelDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for next, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update next to 11.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-37699 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
Is CVE-2021-37699 in your dependencies?
Find it across npm, including transitive dependencies.