CVE-2021-23452: X assign Prototype Pollution Vulnerability

HIGH
Advisory Identifier: GHSA-4mvj-rq4v-2fxw
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CVSS 8.6
CWE-1321 CWE-915
Published
Advisory Summary

CVE-2021-23452 is a HIGH (CVSS 8.6) prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting X assign libraries in the npm ecosystem. The issue involves prototype pollution in x-assign. Remediation is available in the latest vendor maintenance releases.

CVE-2021-23452 at a Glance

CVE Identifier CVE-2021-23452
GHSA Identifier GHSA-4mvj-rq4v-2fxw
Severity HIGH
CVSS v3.1 Base Score 8.6
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product X assign
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.6

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:H/I:L/A:L).

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 Low (I:L)
Availability Low (A:L)

How to Fix CVE-2021-23452

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

x-assign fixed: Latest secure release 
npm install x-assign@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 x-assign

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-23452, inspect your project dependencies using npm:

npm ls x-assign

Analyze the terminal output to locate any version of X assign 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 x-assign 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-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. In X assign, 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

This vulnerability affects all versions of package x-assign. The global proto object can be polluted using the __proto__ object.

CVE-2021-23452 Affected X assign Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
x-assign
npm/x-assign
npm
≤ 0.1.4

References

NVD — CVE-2021-23452 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-23452
X assign Source Repository REPOSITORY
https://github.com/mvoorberg/x-assign
runkit.com/embed/sq8qjwemyn8t WEB
https://runkit.com/embed/sq8qjwemyn8t
snyk.io/vuln/snyk-js-xassig... WEB
https://snyk.io/vuln/SNYK-JS-XASSIGN-1759314

Frequently Asked Questions

What is CVE-2021-23452?
CVE-2021-23452 is a security vulnerability in X assign involving Prototype Pollution in x-assign under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which X assign versions are affected?
Affected versions include releases prior to current release patches across affected packages: x-assign.
What version fixes CVE-2021-23452?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is x-assign affected?
Yes, x-assign 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-2021-23452?
CVE-2021-23452 has a CVSS v3.1 base score of 8.6 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L.
What CWE is associated with CVE-2021-23452?
CVE-2021-23452 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2021-23452?
Run the dependency tree command: 'npm ls x-assign'. 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-4mvj-rq4v-2fxw",
  "modified" : "2022-12-03T03:56:39Z",
  "published" : "2021-10-21T17:50:44Z",
  "aliases" : [ "CVE-2021-23452" ],
  "summary" : "Prototype Pollution in x-assign",
  "details" : "This vulnerability affects all versions of package x-assign. The global proto object can be polluted using the __proto__ object.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "x-assign"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "0.1.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-23452"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mvoorberg/x-assign"
  }, {
    "type" : "WEB",
    "url" : "https://runkit.com/embed/sq8qjwemyn8t"
  }, {
    "type" : "WEB",
    "url" : "https://snyk.io/vuln/SNYK-JS-XASSIGN-1759314"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321", "CWE-915" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-10-21T14:54:57Z",
    "nvd_published_at" : "2021-10-20T13:15:00Z"
  }
}