CVE-2018-3751: Merge recursive Prototype Pollution Vulnerability

CRITICAL
Advisory Identifier: GHSA-cvxm-f295-x957
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CVSS 9.8
CWE-20
Published
Advisory Summary

CVE-2018-3751 is a CRITICAL (CVSS 9.8) prototype pollution vulnerability (CWE-20: Improper Input Validation) affecting Merge recursive libraries in the npm ecosystem. The issue involves prototype pollution in merge-recursive. Remediation is available in the latest vendor maintenance releases.

CVE-2018-3751 at a Glance

CVE Identifier CVE-2018-3751
GHSA Identifier GHSA-cvxm-f295-x957
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-20: Improper Input Validation
Affected Product Merge recursive
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2018-3751

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

merge-recursive fixed: Latest secure release 
npm install merge-recursive@Latest secure release
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 merge-recursive

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2018-3751, inspect your project dependencies using npm:

npm ls merge-recursive

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

Note: The npm ls merge-recursive 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-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In Merge recursive, 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

All versions of `merge-recursive` are vulnerable to Prototype Pollution. When malicious user input is merged with another object it allows the attacker to modify the prototype of Object via `__proto__` causing the addition or modification of an existing property. Proof of concept: ```js var merge = require('merge-recursive').recursive; var malicious_payload = '{"__proto__":{"oops":"It works !"}}'; var a = {}; console.log("Before : " + a.oops); merge({}, JSON.parse(malicious_payload)); console.log("After : " + a.oops); ``` ## Recommendation There is currently no fix available.

CVE-2018-3751 Affected Merge recursive Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
merge-recursive
npm/merge-recursive
npm
≤ 0.0.3

References

NVD — CVE-2018-3751 NVD
https://nvd.nist.gov/vuln/detail/CVE-2018-3751
hackerone.com/reports/311337 WEB
https://hackerone.com/reports/311337
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-cvxm-f295-x957
www.npmjs.com/advisories/715 WEB
https://www.npmjs.com/advisories/715

Frequently Asked Questions

What is CVE-2018-3751?
CVE-2018-3751 is a security vulnerability in Merge recursive involving Prototype Pollution in merge-recursive under CWE-20: Improper Input Validation.
Which Merge recursive versions are affected?
Affected versions include releases prior to current release patches across affected packages: merge-recursive.
What version fixes CVE-2018-3751?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is merge-recursive affected?
Yes, merge-recursive is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2018-3751?
CVE-2018-3751 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2018-3751?
CVE-2018-3751 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check npm dependencies for CVE-2018-3751?
Run the dependency tree command: 'npm ls merge-recursive'. 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-cvxm-f295-x957",
  "modified" : "2023-09-12T18:47:20Z",
  "published" : "2018-09-18T13:46:06Z",
  "aliases" : [ "CVE-2018-3751" ],
  "summary" : "Prototype Pollution in merge-recursive",
  "details" : "All versions of `merge-recursive` are vulnerable to Prototype Pollution. When malicious user input is merged with another object it allows the attacker to modify the prototype of Object via `__proto__` causing the addition or modification of an existing property.\n\nProof of concept:\n\n```js\nvar merge = require('merge-recursive').recursive;\nvar malicious_payload = '{\"__proto__\":{\"oops\":\"It works !\"}}';\n\nvar a = {};\nconsole.log(\"Before : \" + a.oops);\nmerge({}, JSON.parse(malicious_payload));\nconsole.log(\"After : \" + a.oops);\n```\n\n\n## Recommendation\n\nThere is currently no fix available. ",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "merge-recursive"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "0.0.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2018-3751"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/311337"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-cvxm-f295-x957"
  }, {
    "type" : "WEB",
    "url" : "https://www.npmjs.com/advisories/715"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-06-16T21:33:01Z",
    "nvd_published_at" : null
  }
}