CVE-2026-44580: Next Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-gx5p-jg67-6x7h
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2026-44580 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Next libraries in the npm ecosystem. The issue involves next.js has cross-site scripting in beforeinteractive scripts with untrusted input. Remediation is available by upgrading affected packages to version 15.5.16, 16.2.5.

CVE-2026-44580 at a Glance

CVE Identifier CVE-2026-44580
GHSA Identifier GHSA-gx5p-jg67-6x7h
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Next
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 6.1

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:R/S:C/C:L/I:L/A:N).

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

How to Fix CVE-2026-44580

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: 15.5.16 
npm install next@15.5.16
next fixed: 16.2.5 
npm install next@16.2.5
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-2026-44580, 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 15.5.16), 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. 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

### Impact Applications that use `beforeInteractive` scripts together with untrusted content can be vulnerable to cross-site scripting. In affected versions, serialized script content was not escaped safely before being embedded into the document, which could allow attacker-controlled input to break out of the intended script context and execute arbitrary JavaScript in a visitor's browser. ### Fix We now HTML-escape serialized `beforeInteractive` script content before embedding it into the page, preventing attacker-controlled content from breaking out of the inline script boundary. ### Workarounds If you cannot upgrade immediately, do not pass untrusted data into `beforeInteractive` scripts. If that pattern is unavoidable, sanitize or escape the content before embedding it.

CVE-2026-44580 Affected Next Versions

2 component(s)
Fixed Versions:
15.5.1616.2.5
Product / Package Ecosystem Affected Versions Fixed Version
next
npm/next
npm
≥ 13.0.0
< 15.5.16
15.5.16
next
npm/next
npm
≥ 16.0.0
< 16.2.5
16.2.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/vercel/next.js/security/advisories/GHSA-gx5p-jg67-6x7h
NVD — CVE-2026-44580 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-44580
Next Source Repository REPOSITORY
https://github.com/vercel/next.js
Next Release RELEASE
https://github.com/vercel/next.js/releases/tag/v15.5.16
Next Release RELEASE
https://github.com/vercel/next.js/releases/tag/v16.2.5

Frequently Asked Questions

What is CVE-2026-44580?
CVE-2026-44580 is a security vulnerability in Next involving Next.js has cross-site scripting in beforeInteractive scripts with untrusted input under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Next versions are affected?
Affected versions include releases prior to 15.5.16, 16.2.5 across affected packages: next.
What version fixes CVE-2026-44580?
Upgrading to 15.5.16, 16.2.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is next affected?
Yes, next is affected in releases prior to 15.5.16, 16.2.5. Upgrade your dependency to 15.5.16, 16.2.5 or later.
What is the CVSS score of CVE-2026-44580?
CVE-2026-44580 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2026-44580?
CVE-2026-44580 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2026-44580?
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-gx5p-jg67-6x7h",
  "modified" : "2026-05-14T20:38:28Z",
  "published" : "2026-05-11T15:56:38Z",
  "aliases" : [ "CVE-2026-44580" ],
  "summary" : "Next.js has cross-site scripting in beforeInteractive scripts with untrusted input",
  "details" : "### Impact\n\nApplications that use `beforeInteractive` scripts together with untrusted content can be vulnerable to cross-site scripting. In affected versions, serialized script content was not escaped safely before being embedded into the document, which could allow attacker-controlled input to break out of the intended script context and execute arbitrary JavaScript in a visitor's browser.\n\n### Fix\n\nWe now HTML-escape serialized `beforeInteractive` script content before embedding it into the page, preventing attacker-controlled content from breaking out of the inline script boundary.\n\n### Workarounds\n\nIf you cannot upgrade immediately, do not pass untrusted data into `beforeInteractive` scripts. If that pattern is unavoidable, sanitize or escape the content before embedding it.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
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      "ecosystem" : "npm",
      "name" : "next"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "13.0.0"
      }, {
        "fixed" : "15.5.16"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "next"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
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      }, {
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      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/security/advisories/GHSA-gx5p-jg67-6x7h"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44580"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/vercel/next.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/releases/tag/v15.5.16"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/releases/tag/v16.2.5"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-11T15:56:38Z",
    "nvd_published_at" : "2026-05-13T18:16:18Z"
  }
}