CVE-2026-27979: Next Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-h27x-g6w4-24gq
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CWE-770
Published
Advisory Summary

CVE-2026-27979 is a MODERATE denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Next libraries in the npm ecosystem. The issue involves unbounded postponed resume buffering can lead to dos. Remediation is available by upgrading affected packages to version 16.1.7.

CVE-2026-27979 at a Glance

CVE Identifier CVE-2026-27979
GHSA Identifier GHSA-h27x-g6w4-24gq
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-2026-27979

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: 16.1.7 
npm install next@16.1.7
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-2026-27979, 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 16.1.7), 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

## Summary A request containing the `next-resume: 1` header (corresponding with a PPR resume request) would buffer request bodies without consistently enforcing `maxPostponedStateSize` in certain setups. The previous mitigation protected minimal-mode deployments, but equivalent non-minimal deployments remained vulnerable to the same unbounded postponed resume-body buffering behavior. ## Impact In applications using the App Router with Partial Prerendering capability enabled (via `experimental.ppr` or `cacheComponents`), an attacker could send oversized `next-resume` POST payloads that were buffered without consistent size enforcement in non-minimal deployments, causing excessive memory usage and potential denial of service. ## Patches Fixed by enforcing size limits across all postponed-body buffering paths and erroring when limits are exceeded. ## Workarounds If upgrade is not immediately possible: - Block requests containing the `next-resume` header, as this is never valid to be sent from an untrusted client.

CVE-2026-27979 Affected Next Versions

1 component(s)
Fixed Versions:
16.1.7
Product / Package Ecosystem Affected Versions Fixed Version
next
npm/next
npm
≥ 16.0.1
< 16.1.7
16.1.7

References

GitHub Advisory / Wiki ADVISORY
https://github.com/vercel/next.js/security/advisories/GHSA-h27x-g6w4-24gq
NVD — CVE-2026-27979 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27979
Security Fix Commit FIX COMMIT
https://github.com/vercel/next.js/commit/c885d4825f800dd1e49ead37274dcd08cdd6f3f1
Next Source Repository REPOSITORY
https://github.com/vercel/next.js
Next Release RELEASE
https://github.com/vercel/next.js/releases/tag/v16.1.7

Frequently Asked Questions

What is CVE-2026-27979?
CVE-2026-27979 is a security vulnerability in Next involving Unbounded postponed resume buffering can lead to DoS under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Next versions are affected?
Affected versions include releases prior to 16.1.7 across affected packages: next.
What version fixes CVE-2026-27979?
Upgrading to 16.1.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is next affected?
Yes, next is affected in releases prior to 16.1.7. Upgrade your dependency to 16.1.7 or later.
What CWE is associated with CVE-2026-27979?
CVE-2026-27979 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-2026-27979?
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-h27x-g6w4-24gq",
  "modified" : "2026-03-19T18:31:02Z",
  "published" : "2026-03-17T16:16:49Z",
  "aliases" : [ "CVE-2026-27979" ],
  "summary" : "Next.js: Unbounded postponed resume buffering can lead to DoS",
  "details" : "## Summary\nA request containing the `next-resume: 1` header (corresponding with a PPR resume request) would buffer request bodies without consistently enforcing `maxPostponedStateSize` in certain setups. The previous mitigation protected minimal-mode deployments, but equivalent non-minimal deployments remained vulnerable to the same unbounded postponed resume-body buffering behavior.\n\n## Impact\nIn applications using the App Router with Partial Prerendering capability enabled (via `experimental.ppr` or `cacheComponents`), an attacker could send oversized `next-resume` POST payloads that were buffered without consistent size enforcement in non-minimal deployments, causing excessive memory usage and potential denial of service.\n\n## Patches\nFixed by enforcing size limits across all postponed-body buffering paths and erroring when limits are exceeded.  \n\n## Workarounds\nIf upgrade is not immediately possible:\n- Block requests containing the `next-resume` header, as this is never valid to be sent from an untrusted client.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/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" : "16.0.1"
      }, {
        "fixed" : "16.1.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/security/advisories/GHSA-h27x-g6w4-24gq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27979"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/commit/c885d4825f800dd1e49ead37274dcd08cdd6f3f1"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/vercel/next.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/next.js/releases/tag/v16.1.7"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-17T16:16:49Z",
    "nvd_published_at" : "2026-03-18T01:16:04Z"
  }
}