CVE-2021-25948: Expand hash Prototype Pollution Vulnerability

CRITICAL
Advisory Identifier: GHSA-x3wr-v4wx-5qpc
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CVSS 9.8
CWE-1321 CWE-915
Published
Advisory Summary

CVE-2021-25948 is a CRITICAL (CVSS 9.8) prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Expand hash libraries in the npm ecosystem. The issue involves prototype pollution. Remediation is available in the latest vendor maintenance releases.

CVE-2021-25948 at a Glance

CVE Identifier CVE-2021-25948
GHSA Identifier GHSA-x3wr-v4wx-5qpc
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Expand hash
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:3.1/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-2021-25948

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

expand-hash fixed: Latest secure release 
npm install expand-hash@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 expand-hash

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-25948, inspect your project dependencies using npm:

npm ls expand-hash

Analyze the terminal output to locate any version of Expand hash 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 expand-hash 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 Expand hash, 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

Prototype pollution vulnerability in ‘expand-hash’ versions 0.1.0 through 1.0.1 allows an attacker to cause a denial of service and may lead to remote code execution.

CVE-2021-25948 Affected Expand hash Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
expand-hash
npm/expand-hash
npm
≤ 1.0.1

References

NVD — CVE-2021-25948 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-25948
Expand hash Source Repository REPOSITORY
https://github.com/doowb/expand-hash
Expand hash Source Repository REPOSITORY
https://github.com/doowb/expand-hash/blob/556913f6c2f05848110b5b8261cfc78e5ce3dc77/index.js#L19
www.whitesourcesoftware.com/vulnerability-datab... WEB
https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25948

Frequently Asked Questions

What is CVE-2021-25948?
CVE-2021-25948 is a security vulnerability in Expand hash involving Prototype Pollution under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Expand hash versions are affected?
Affected versions include releases prior to current release patches across affected packages: expand-hash.
What version fixes CVE-2021-25948?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is expand-hash affected?
Yes, expand-hash 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-2021-25948?
CVE-2021-25948 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-25948?
CVE-2021-25948 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-2021-25948?
Run the dependency tree command: 'npm ls expand-hash'. 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-x3wr-v4wx-5qpc",
  "modified" : "2022-06-29T20:41:54Z",
  "published" : "2021-06-21T17:14:01Z",
  "aliases" : [ "CVE-2021-25948" ],
  "summary" : "Prototype Pollution",
  "details" : "Prototype pollution vulnerability in ‘expand-hash’ versions 0.1.0 through 1.0.1 allows an attacker to cause a denial of service and may lead to remote code execution.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "expand-hash"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.0.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-25948"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/doowb/expand-hash"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/doowb/expand-hash/blob/556913f6c2f05848110b5b8261cfc78e5ce3dc77/index.js#L19"
  }, {
    "type" : "WEB",
    "url" : "https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25948"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321", "CWE-915" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-06-14T19:29:17Z",
    "nvd_published_at" : "2021-06-10T12:15:00Z"
  }
}