GHSA-vxf5-wxwp-m7g9 CVE-2021-37699

Open Redirect in Next.js

Medium npm

Severity: 6.9 / 10; Medium · CVSS 3.1
Exploit chance (EPSS): 1.03%; Chance of exploitation in the next 30 days. Higher than 63.79% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-601 URL Redirection to Untrusted Site ('Open Redirect')
Fix: 11.1.0; Upgrade next to this version or later

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 it can allow for phishing attacks by redirecting to an attacker's domain from a trusted domain.

Impact

Affected: Users of Next.js between 10.0.5 and 10.2.0
Affected: Users of Next.js between 11.0.0 and 11.0.1 using pages/_error.js without getInitialProps
Affected: Users of Next.js between 11.0.0 and 11.0.1 using pages/_error.js and next 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 next npm 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

https://github.com/vercel/next.js/releases/tag/v11.1.0

Affected versions

npm

Package	Vulnerable	Fixed in
next	`>= 0.9.9, < 11.1.0`	`11.1.0`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

next npm → `11.1.0`

npm

npm install next@11.1.0

yarn

yarn add next@11.1.0

pnpm

pnpm add next@11.1.0

Severity breakdown

CVSS 3.1 6.9

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

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: Required
Scope: Changed
Confidentiality: High
Integrity: Low
Availability: None

Weakness

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

The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

How to prevent it

Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. Use a list of approved URLs or domains to be used for redirection.
Architecture and Design: Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
Architecture and Design: When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to "/login.asp" and ID 2 could map to "http://www.example.com/". Features such as the ESAPI AccessReferenceMap [REF-45] provide this capability.
Architecture and Design: Ensure that no externally-supplied requests are honored by requiring that all redirect requests include a unique nonce generated by the application [REF-483]. Be sure that the nonce is not predictable (CWE-330).
Architecture and Design, Implementation: Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls. Many open redirect problems occur because the programmer assumed that certain inputs could not be modified, such as cookies and hidden form fields.
Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2021-37699

Packages

github.com/vercel/next.js

Timeline

Aug 12, 2021 Published
Jul 8, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-673q-mjm6-r5xr Next.js: Unauthenticated Remote Code Execution in `use cache` functions returning typed arrays	Critical	Also affects next
GHSA-2464-fhr4-w9xw Next.js: Unauthenticated Remote Code Execution in Image Optimization API when SVG files are used	Critical	Also affects next
GHSA-p3m5-59mp-jv5r Next.js: Denial of Service in App Router using Server Actions	High	Also affects next
GHSA-3w37-wq28-93x7 Next.js: Pending `use cache` fill can leak Draft Mode content into regular responses and persisted pages	Medium	Also affects next
GHSA-4jqv-mc3x-m676 Next.js has cache poisoning of SSG and ISR pages in self-hosted applications	Medium	Also affects next
GHSA-39w2-rjm5-chcv Next.js has information disclosure in development server's Model Context Protocol endpoint	Medium	Also affects next
GHSA-f87g-xv8r-7p7x Next.js has information disclosure in App Router metadata image routes via dynamicParams bypass	Medium	Also affects next
GHSA-mcj8-r9mp-w47p Next.js has cache poisoning in SSG/ISR rendering that leads to cross-user content substitution and persistent denial of service	Medium	Also affects next

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