# CVE-2021-37699: Open Redirect in Next.js versions below 11.1.0

> Attackers can redirect users to malicious sites via specially encoded paths in statically generated error pages, facilitating phishing attacks.

- **Severity:** Medium 6.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 11 Aug 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-vxf5-wxwp-m7g9

## What is CVE-2021-37699?

CVE-2021-37699 is a medium-severity vulnerability in Vercel Next.js, published on 11 Aug 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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 can allow for phishing attacks by redirecting to an attacker's domain from a trusted domain. We recommend everyone to upgrade regardless of whether you can reproduce the issue or not. The issue has been patched in release 11.1.0.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2021-37699?

2 open source packages ship an affected version, including next. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `next` | npm | From 0.9.9 | 11.1.0 |
| `next` | npm | From 0.9.9 | 11.1.0 |

Products: Vercel Next.js.

## How do I fix CVE-2021-37699?

Upgrade next to 11.1.0 or later.

## Is CVE-2021-37699 being exploited?

There is no known exploitation of CVE-2021-37699 in the wild and no public exploit code.

## Other vulnerabilities in Vercel Next.js

- [CVE-2025-29927](https://insights.sbomify.com/CVE-2025-29927/): Authorization Bypass in Next.js Middleware (critical 9.1)
- [CVE-2026-44578](https://insights.sbomify.com/CVE-2026-44578/): Next.js: Server-side request forgery in applications using WebSocket upgrades (high 8.6)
- [CVE-2026-94483](https://insights.sbomify.com/CVE-2026-94483/): Next.js: Server-Side Request Forgery in Image Optimization (high 8.3)
- [CVE-2026-64642](https://insights.sbomify.com/CVE-2026-64642/): Next.js: Middleware / Proxy bypass in App Router applications using Turbopack and single locale (high 8.3)
- [CVE-2026-64645](https://insights.sbomify.com/CVE-2026-64645/): Next.js: Server-Side Request Forgery in rewrites via attacker-controlled destination hostname (high 8.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-37699 and fix it if it is affected.

What it is: CVE-2021-37699 is a medium-severity vulnerability in Vercel Next.js, published on 11 Aug 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-37699 in the wild and no public exploit code.

Affected packages and fixed versions:
- next (npm): affected from 0.9.9; fixed in 11.1.0
- next (npm): affected from 0.9.9; fixed in 11.1.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-37699/ (Markdown: https://insights.sbomify.com/CVE-2021-37699/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37699
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37699
- OSV: https://osv.dev/vulnerability/CVE-2021-37699

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-37699/
Summaries are generated and may contain mistakes; the official description above is the record.