CVE-2026-40879: @nestjs/microservices Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-hpwf-8g29-85qm
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CVSS 7.5
CWE-770 CWE-674
Published
Advisory Summary

CVE-2026-40879 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting @nestjs/microservices libraries in the npm ecosystem. The issue involves nest affected by dos via recursive handledata in jsonsocket (tcp transport). Remediation is available by upgrading affected packages to version 11.1.19.

CVE-2026-40879 at a Glance

CVE Identifier CVE-2026-40879
GHSA Identifier GHSA-hpwf-8g29-85qm
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product @nestjs/microservices
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-2026-40879

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

@nestjs/microservices fixed: 11.1.19 
npm install @nestjs/microservices@11.1.19
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 @nestjs/microservices

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-40879, inspect your project dependencies using npm:

npm ls @nestjs/microservices

Analyze the terminal output to locate any version of @nestjs/microservices in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 11.1.19), your application is affected.

Note: The npm ls @nestjs/microservices 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 @nestjs/microservices, 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 Attacker sends many small, valid JSON messages in one TCP frame → handleData() recurses once per message; buffer shrinks each call → maxBufferSize is never reached; call stack overflows instead → A ~47 KB payload is sufficient to trigger RangeError ### Patches Fixed in `@nestjs/microservices@11.1.19` ### References Discovered by https://github.com/hwpark6804-gif

CVE-2026-40879 Affected @nestjs/microservices Versions

1 component(s)
Fixed Versions:
11.1.19
Product / Package Ecosystem Affected Versions Fixed Version
@nestjs/microservices
npm/@nestjs/microservices
npm
< 11.1.19
11.1.19

References

GitHub Advisory / Wiki ADVISORY
https://github.com/nestjs/nest/security/advisories/GHSA-hpwf-8g29-85qm
NVD — CVE-2026-40879 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40879
@nestjs/microservices Source Repository REPOSITORY
https://github.com/nestjs/nest

Frequently Asked Questions

What is CVE-2026-40879?
CVE-2026-40879 is a security vulnerability in @nestjs/microservices involving Nest Affected by DoS via Recursive handleData in JsonSocket (TCP Transport) under CWE-770: Allocation of Resources Without Limits or Throttling.
Which @nestjs/microservices versions are affected?
Affected versions include releases prior to 11.1.19 across affected packages: @nestjs/microservices.
What version fixes CVE-2026-40879?
Upgrading to 11.1.19 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @nestjs/microservices affected?
Yes, @nestjs/microservices is affected in releases prior to 11.1.19. Upgrade your dependency to 11.1.19 or later.
What is the CVSS score of CVE-2026-40879?
CVE-2026-40879 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-2026-40879?
CVE-2026-40879 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-2026-40879?
Run the dependency tree command: 'npm ls @nestjs/microservices'. 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-hpwf-8g29-85qm",
  "modified" : "2026-04-27T16:16:57Z",
  "published" : "2026-04-14T00:15:09Z",
  "aliases" : [ "CVE-2026-40879" ],
  "summary" : "Nest Affected by DoS via Recursive handleData in JsonSocket (TCP Transport)",
  "details" : "### Impact\nAttacker sends many small, valid JSON messages in one TCP frame\n → handleData() recurses once per message; buffer shrinks each call\n → maxBufferSize is never reached; call stack overflows instead\n → A ~47 KB payload is sufficient to trigger RangeError\n\n### Patches\n\nFixed in `@nestjs/microservices@11.1.19`\n\n### References\n\nDiscovered by https://github.com/hwpark6804-gif",
  "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" : "@nestjs/microservices"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "11.1.19"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 11.1.18"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nestjs/nest/security/advisories/GHSA-hpwf-8g29-85qm"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-40879"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/nestjs/nest"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-674", "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-14T00:15:09Z",
    "nvd_published_at" : "2026-04-21T20:17:01Z"
  }
}