CVE-2025-49826: Next Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-67rr-84xm-4c7r
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CVSS 7.5
CWE-444
Published
Advisory Summary

CVE-2025-49826 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')) affecting Next libraries in the npm ecosystem. The issue involves next.js vulnerability can lead to dos via cache poisoning. Remediation is available by upgrading affected packages to version 15.1.8.

CVE-2025-49826 at a Glance

CVE Identifier CVE-2025-49826
GHSA Identifier GHSA-67rr-84xm-4c7r
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected Product Next
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2025-49826

To remediate this vulnerability, upgrade all affected Next dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

next fixed: 15.1.8 
npm install next@15.1.8
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls next

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2025-49826, inspect your project dependencies using npm:

npm ls next

Analyze the terminal output to locate any version of Next in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 15.1.8), your application is affected.

Note: The npm ls next command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling'), where 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. In Next, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary A vulnerability affecting Next.js has been addressed. It impacted versions 15.0.4 through 15.1.8 and involved a cache poisoning bug leading to a Denial of Service (DoS) condition. Under certain conditions, this issue may allow a HTTP 204 response to be cached for static pages, leading to the 204 response being served to all users attempting to access the page More details: [CVE-2025-49826](https://vercel.com/changelog/cve-2025-49826) ## Credits - Allam Rachid [zhero;](https://zhero-web-sec.github.io/research-and-things/) - Allam Yasser (inzo)

CVE-2025-49826 Affected Next Versions

1 component(s)
Fixed Versions:
15.1.8
Product / Package Ecosystem Affected Versions Fixed Version
next
npm/next
npm
≥ 15.0.4-canary.51
< 15.1.8
15.1.8

References

GitHub Advisory / Wiki ADVISORY
https://github.com/vercel/next.js/security/advisories/GHSA-67rr-84xm-4c7r
NVD — CVE-2025-49826 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-49826
Security Fix Commit FIX COMMIT
https://github.com/vercel/next.js/commit/16bfce64ef2157f2c1dfedcfdb7771bc63103fd2
Security Fix Commit FIX COMMIT
https://github.com/vercel/next.js/commit/a15b974ed707d63ad4da5b74c1441f5b7b120e93
Next Source Repository REPOSITORY
https://github.com/vercel/next.js
Next Release RELEASE
https://github.com/vercel/next.js/releases/tag/v15.1.8
vercel.com/changelog/cve-2025-... WEB
https://vercel.com/changelog/cve-2025-49826

Frequently Asked Questions

What is CVE-2025-49826?
CVE-2025-49826 is a security vulnerability in Next involving Next.JS vulnerability can lead to DoS via cache poisoning under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling').
Which Next versions are affected?
Affected versions include releases prior to 15.1.8 across affected packages: next.
What version fixes CVE-2025-49826?
Upgrading to 15.1.8 (or the latest patched release for your respective branch) resolves the vulnerability.
Is next affected?
Yes, next is affected in releases prior to 15.1.8. Upgrade your dependency to 15.1.8 or later.
What is the CVSS score of CVE-2025-49826?
CVE-2025-49826 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2025-49826?
CVE-2025-49826 is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') (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.).
How can I check npm dependencies for CVE-2025-49826?
Run the dependency tree command: 'npm ls next'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-67rr-84xm-4c7r",
  "modified" : "2025-07-03T21:49:52Z",
  "published" : "2025-07-03T21:14:48Z",
  "aliases" : [ "CVE-2025-49826" ],
  "summary" : "Next.JS vulnerability can lead to DoS via cache poisoning ",
  "details" : "### Summary\nA vulnerability affecting Next.js has been addressed. It impacted versions 15.0.4 through 15.1.8 and involved a cache poisoning bug leading to a Denial of Service (DoS) condition.\n\nUnder certain conditions, this issue may allow a HTTP 204 response to be cached for static pages, leading to the 204 response being served to all users attempting to access the page\n\nMore details: [CVE-2025-49826](https://vercel.com/changelog/cve-2025-49826)\n\n## Credits\n- Allam Rachid [zhero;](https://zhero-web-sec.github.io/research-and-things/)\n- Allam Yasser (inzo)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "next"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "15.0.4-canary.51"
      }, {
        "fixed" : "15.1.8"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/security/advisories/GHSA-67rr-84xm-4c7r"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-49826"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/commit/16bfce64ef2157f2c1dfedcfdb7771bc63103fd2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/commit/a15b974ed707d63ad4da5b74c1441f5b7b120e93"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/vercel/next.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/releases/tag/v15.1.8"
  }, {
    "type" : "WEB",
    "url" : "https://vercel.com/changelog/cve-2025-49826"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-444" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-07-03T21:14:48Z",
    "nvd_published_at" : "2025-07-03T21:15:27Z"
  }
}