vercel next.js up to 15.3.2 React Server request smuggling

Summaryinfo

A vulnerability classified as problematic was found in vercel next.js up to 15.3.2. Affected by this issue is some unknown functionality of the component React Server Component. The manipulation results in request smuggling. This vulnerability is reported as CVE-2025-49005. The attack can be launched remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, was found in vercel next.js up to 15.3.2. Affected is an unknown function of the component React Server Component. The manipulation with an unknown input leads to a request smuggling vulnerability. CWE is classifying the issue as CWE-444. The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. This is going to have an impact on integrity. CVE summarizes:

Next.js is a React framework for building full-stack web applications. In Next.js App Router from 15.3.0 to before 15.3.3 and Vercel CLI from 41.4.1 to 42.2.0, a cache poisoning vulnerability was found. The issue allowed page requests for HTML content to return a React Server Component (RSC) payload instead under certain conditions. When deployed to Vercel, this would only impact the browser cache, and would not lead to the CDN being poisoned. When self-hosted and deployed externally, this could lead to cache poisoning if the CDN does not properly distinguish between RSC / HTML in the cache keys. This issue has been resolved in Next.js 15.3.3.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2025-49005 since 05/29/2025. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available.

Upgrading to version 15.3.3 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch ec202eccf05820b60c6126d6411fe16766ecc066 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-19911). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• JavaScript Library

Vendor

• vercel

Name

• next.js

Version

• 15.3.0
• 15.3.1
• 15.3.2

License

• open-source

Website

• Product: https://github.com/vercel/next.js/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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