How severe is CVE-2021-37699?

CVE-2021-37699 has a CVSS 3.x base score of 6.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2021-37699 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-37699?

CVE-2021-37699 affects Vercel Next.js. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-37699?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-37699 published?

CVE-2021-37699 was published on 2021-08-12 and last updated on 2026-06-17.

CVE-2021-37699

CVE-2021-37699 is a medium-severity vulnerability in Vercel Next.js with a CVSS 3.x base score of 6.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-601.

Key facts

Severity: Medium (CVSS 3.x base score 6.9)
CVSS v2: 5.8
EPSS exploit prediction: 1% (64th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-601
Affected product: Vercel Next.js
Published: 2021-08-12
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-37699?: 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.
How severe is CVE-2021-37699?: CVE-2021-37699 has a CVSS 3.x base score of 6.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2021-37699 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-37699?: CVE-2021-37699 affects Vercel Next.js. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-37699?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-37699 published?: CVE-2021-37699 was published on 2021-08-12 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:vercel:next.js:*:*:*:*:*:node.js:*:*

More vulnerabilities in Vercel Next.js

CVE-2025-55182 — Critical (CVSS 10.0): A pre-authentication remote code execution vulnerability exists in React Server Components versions 19.0.0, 19.1.0,…
CVE-2025-29927 — Critical (CVSS 9.1): Next.js is a React framework for building full-stack web applications. Starting in version 1.11.4 and prior to versions…
CVE-2026-44578 — High (CVSS 8.6): Next.js is a React framework for building full-stack web applications. From 13.4.13 to before 15.5.16 and 16.2.5,…
CVE-2026-44574 — High (CVSS 8.1): Next.js is a React framework for building full-stack web applications. From 15.4.0 to before 15.5.16 and 16.2.5,…
CVE-2026-45109 — High (CVSS 7.5): Next.js is a React framework for building full-stack web applications. From 15.2.0 to before 15.5.18 and 16.2.6, it was…
CVE-2026-44579 — High (CVSS 7.5): Next.js is a React framework for building full-stack web applications. From to before 15.5.16 and 16.2.5, applications…

All CVEs affecting Vercel Next.js →

Other CWE-601 (Open Redirect) vulnerabilities

CVE-2018-3774 — Critical (CVSS 10.0): Incorrect parsing in url-parse <1.4.3 returns wrong hostname which leads to multiple vulnerabilities such as SSRF, Open…
CVE-2019-25282 — Critical (CVSS 9.8): V-SOL GPON/EPON OLT Platform v2.03 contains an open redirect vulnerability in the script that allows attackers to…
CVE-2020-36912 — Critical (CVSS 9.8): Plexus anblick Digital Signage Management 3.1.13 contains an open redirect vulnerability in the 'PantallaLogin' script…
CVE-2025-43526 — Critical (CVSS 9.8): This issue was addressed with improved URL validation. This issue is fixed in Safari 26.2, macOS Tahoe 26.2. On a Mac…
CVE-2025-55031 — Critical (CVSS 9.8): Malicious pages could use Firefox for iOS to pass FIDO: links to the OS and trigger the hybrid passkey transport. An…
CVE-2024-22891 — Critical (CVSS 9.8): Nteract v.0.28.0 was discovered to contain a remote code execution (RCE) vulnerability via the Markdown link.

Browse all CWE-601 (Open Redirect) vulnerabilities →