CVE-2020-36048: Engine.io Remote Code Execution Vulnerability

HIGH
Advisory Identifier: GHSA-j4f2-536g-r55m
Share
CVSS 7.5
CWE-400
Published
Advisory Summary

CVE-2020-36048 is a HIGH (CVSS 7.5) remote code execution vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Engine.io libraries in the npm ecosystem. The issue involves resource exhaustion in engine.io. Remediation is available by upgrading affected packages to version 3.6.0.

CVE-2020-36048 at a Glance

CVE Identifier CVE-2020-36048
GHSA Identifier GHSA-j4f2-536g-r55m
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Engine.io
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-2020-36048

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

engine.io fixed: 3.6.0 
npm install engine.io@3.6.0
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 engine.io

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-36048, inspect your project dependencies using npm:

npm ls engine.io

Analyze the terminal output to locate any version of Engine.io in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.6.0), your application is affected.

Note: The npm ls engine.io 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-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In Engine.io, 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

Engine.IO before 4.0.0 and 3.6.0 allows attackers to cause a denial of service (resource consumption) via a POST request to the long polling transport.

CVE-2020-36048 Affected Engine.io Versions

1 component(s)
Fixed Versions:
3.6.0
Product / Package Ecosystem Affected Versions Fixed Version
engine.io
npm/engine.io
npm
< 3.6.0
3.6.0

References

NVD — CVE-2020-36048 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-36048
Security Fix Commit FIX COMMIT
https://github.com/socketio/engine.io/commit/58e274c437e9cbcf69fd913c813aad8fbd253703
Security Fix Commit FIX COMMIT
https://github.com/socketio/engine.io/commit/734f9d1268840722c41219e69eb58318e0b2ac6b
blog.caller.xyz/socketio-engineio-d... WEB
https://blog.caller.xyz/socketio-engineio-dos
Engine.io Source Repository REPOSITORY
https://github.com/bcaller/kill-engine-io
Engine.io Source Repository REPOSITORY
https://github.com/socketio/engine.io

Frequently Asked Questions

What is CVE-2020-36048?
CVE-2020-36048 is a security vulnerability in Engine.io involving Resource exhaustion in engine.io under CWE-400: Uncontrolled Resource Consumption.
Which Engine.io versions are affected?
Affected versions include releases prior to 3.6.0 across affected packages: engine.io.
What version fixes CVE-2020-36048?
Upgrading to 3.6.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is engine.io affected?
Yes, engine.io is affected in releases prior to 3.6.0. Upgrade your dependency to 3.6.0 or later.
What is the CVSS score of CVE-2020-36048?
CVE-2020-36048 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-2020-36048?
CVE-2020-36048 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check npm dependencies for CVE-2020-36048?
Run the dependency tree command: 'npm ls engine.io'. 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-j4f2-536g-r55m",
  "modified" : "2025-05-29T23:06:32Z",
  "published" : "2022-02-09T22:29:04Z",
  "aliases" : [ "CVE-2020-36048" ],
  "summary" : "Resource exhaustion in engine.io",
  "details" : "Engine.IO before 4.0.0 and 3.6.0 allows attackers to cause a denial of service (resource consumption) via a POST request to the long polling transport.",
  "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" : "engine.io"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.6.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-36048"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/socketio/engine.io/commit/58e274c437e9cbcf69fd913c813aad8fbd253703"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/socketio/engine.io/commit/734f9d1268840722c41219e69eb58318e0b2ac6b"
  }, {
    "type" : "WEB",
    "url" : "https://blog.caller.xyz/socketio-engineio-dos"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/bcaller/kill-engine-io"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/socketio/engine.io"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-04-06T22:58:33Z",
    "nvd_published_at" : "2021-01-08T00:15:00Z"
  }
}