CVE-2026-94485: Next.js Information Disclosure via DynamicParams Bypass in App Router Metadata Image Routes
Summary
CVE-2026-94485: Next.js has information disclosure in App Router metadata image routes via dynamicParams bypass. Affects next versions >= 16.0.0, < 16.3.8. Fixed in 16.3.8. How to fix ↓
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Background
Next.js is a popular React framework that enables developers to build server-rendered applications with ease. It provides features such as automatic code splitting, server-side rendering, and static site generation. However, certain vulnerabilities can arise in its routing system, particularly in the App Router, which manages dynamic routes and metadata image generation.
Vulnerability Detail
The vulnerability arises from the App Router in Next.js applications built with webpack, where metadata image routes like opengraph-image and twitter-image do not respect the 'dynamicParams' route segment option. This oversight allows attackers to access metadata image URLs for dynamic segments that should have been excluded from the 'generateStaticParams()' function. The potential ramifications include unauthorized access to sensitive information that could be embedded in these images, leading to information disclosure.
How To Fix
Latest published version: 16.4.2 as of 22 Oct 2026
npm install next@16.4.2Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
16.3.8
This is the first release that contains the fix.
npm install next@16.3.8Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, you can manually validate the dynamic parameters in your application to ensure that only authorized segments are processed for metadata image routes. This can be done by implementing custom logic in your route handling to check against a whitelist of allowed parameters.
Conclusion
In summary, CVE-2026-94485 is a moderate severity vulnerability in Next.js that allows for information disclosure through improperly handled metadata image routes. It is crucial to update to the patched version to mitigate this risk and ensure the security of your application.
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FAQ
CVE-2026-94485 is a vulnerability in Next.js that allows information disclosure through a bypass of the dynamicParams option in App Router metadata image routes.
If your application uses Next.js with affected versions, it may expose sensitive information through metadata images that should not be publicly accessible.
The vulnerability affects Next.js versions from 16.0.0 up to, but not including, 16.3.8.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. By checking your package-lock.json file, you can identify if your application is affected by this vulnerability.
Yes, you can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
References
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