CVE-2026-64646: Next Unbounded Server Action Payload Vulnerability

MODERATE
Advisory Identifier: GHSA-4c39-4ccg-62r3
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CWE-770
Published
Advisory Summary

CVE-2026-64646 is a MODERATE unbounded server action payload vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Next libraries in the npm ecosystem. The issue involves unbounded server action payload in edge runtime. Remediation is available by upgrading affected packages to version 15.5.21, 16.2.11.

CVE-2026-64646 at a Glance

CVE Identifier CVE-2026-64646
GHSA Identifier GHSA-4c39-4ccg-62r3
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Next
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-64646

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: 15.5.21 
npm install next@15.5.21
next fixed: 16.2.11 
npm install next@16.2.11
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-2026-64646, 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 15.5.21), 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-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. 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 Requests targeting Next.js applications using App Router with at least one Server Action can lead to excessive memory consumption if that Server Actions uses the Edge runtime ## Workarounds If you cannot upgrade, ensure your hosting provider limits the request's body size. 5 MiB should be allowed at max by your hosting provider.

CVE-2026-64646 Affected Next Versions

2 component(s)
Fixed Versions:
15.5.2116.2.11
Product / Package Ecosystem Affected Versions Fixed Version
next
npm/next
npm
≥ 13.0.0
< 15.5.21
15.5.21
next
npm/next
npm
≥ 16.0.0
< 16.2.11
16.2.11

References

GitHub Advisory / Wiki ADVISORY
https://github.com/vercel/next.js/security/advisories/GHSA-4c39-4ccg-62r3
Security Fix Commit FIX COMMIT
https://github.com/vercel/next.js/commit/57c31f724d746e86a9e8b92aa8be538a922446a4
Security Fix Commit FIX COMMIT
https://github.com/vercel/next.js/commit/9a4651e754f70b12e397694ffc41f44c3ba8cc17
Next Source Repository REPOSITORY
https://github.com/vercel/next.js
Next Release RELEASE
https://github.com/vercel/next.js/releases/tag/v15.5.21
Next Release RELEASE
https://github.com/vercel/next.js/releases/tag/v16.2.11

Frequently Asked Questions

What is CVE-2026-64646?
CVE-2026-64646 is a security vulnerability in Next involving Unbounded Server Action payload in Edge runtime under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Next versions are affected?
Affected versions include releases prior to 15.5.21, 16.2.11 across affected packages: next.
What version fixes CVE-2026-64646?
Upgrading to 15.5.21, 16.2.11 (or the latest patched release for your respective branch) resolves the vulnerability.
Is next affected?
Yes, next is affected in releases prior to 15.5.21, 16.2.11. Upgrade your dependency to 15.5.21, 16.2.11 or later.
What CWE is associated with CVE-2026-64646?
CVE-2026-64646 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check npm dependencies for CVE-2026-64646?
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-4c39-4ccg-62r3",
  "modified" : "2026-07-22T23:02:43Z",
  "published" : "2026-07-22T23:02:43Z",
  "aliases" : [ "CVE-2026-64646" ],
  "summary" : "Next.js: Unbounded Server Action payload in Edge runtime",
  "details" : "## Impact\n\nRequests targeting Next.js applications using App Router with at least one Server Action can lead to excessive memory consumption if that Server Actions uses the Edge runtime\n\n## Workarounds\n\nIf you cannot upgrade, ensure your hosting provider limits the request's body size. 5 MiB should be allowed at max by your hosting provider.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "next"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "13.0.0"
      }, {
        "fixed" : "15.5.21"
      } ]
    } ]
  }, {
    "package" : {
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    },
    "ranges" : [ {
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      "events" : [ {
        "introduced" : "16.0.0"
      }, {
        "fixed" : "16.2.11"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/security/advisories/GHSA-4c39-4ccg-62r3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/commit/57c31f724d746e86a9e8b92aa8be538a922446a4"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/commit/9a4651e754f70b12e397694ffc41f44c3ba8cc17"
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    "type" : "PACKAGE",
    "url" : "https://github.com/vercel/next.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/releases/tag/v15.5.21"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/releases/tag/v16.2.11"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-22T23:02:43Z",
    "nvd_published_at" : null
  }
}