Vulnerabilities in pkg:npm/json-schema

PACKAGE
Advisory Identifier: GHSA-896r-f27r-55mw
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Advisory Summary

CVE-2021-3918 is a CRITICAL (CVSS 9.8) json-schema is vulnerable to prototype vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Json schema libraries in the npm ecosystem. The issue involves json-schema is vulnerable to prototype pollution. Remediation is available by upgrading affected packages to version 0.4.0.

1 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/json-schema

1 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/json-schema. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-896r-f27r-55mw CVE-2021-3918 CRITICAL json-schema is vulnerable to Prototype Pollution

CVE-2021-3918 at a Glance

CVE Identifier CVE-2021-3918
GHSA Identifier GHSA-896r-f27r-55mw
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Json schema
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-2021-3918

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

json-schema fixed: 0.4.0 
npm install json-schema@0.4.0
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 json-schema

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-3918, inspect your project dependencies using npm:

npm ls json-schema

Analyze the terminal output to locate any version of Json schema in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.4.0), your application is affected.

Note: The npm ls json-schema 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 Json schema, 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

json-schema before version 0.4.0 is vulnerable to Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').

CVE-2021-3918 Affected Json schema Versions

1 component(s)
Fixed Versions:
0.4.0
Product / Package Ecosystem Affected Versions Fixed Version
json-schema
npm/json-schema
npm
< 0.4.0
0.4.0

References

NVD — CVE-2021-3918 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3918
Security Fix Commit FIX COMMIT
https://github.com/kriszyp/json-schema/commit/22f146111f541d9737e832823699ad3528ca7741
Security Fix Commit FIX COMMIT
https://github.com/kriszyp/json-schema/commit/b62f1da1ff5442f23443d6be6a92d00e65cba93a
Security Fix Commit FIX COMMIT
https://github.com/kriszyp/json-schema/commit/f6f6a3b02d667aa4ba2d5d50cc19208c4462abfa
Json schema Source Repository REPOSITORY
https://github.com/kriszyp/json-schema
huntr.dev/bounties/bb6ccd63-f... WEB
https://huntr.dev/bounties/bb6ccd63-f505-4e3a-b55f-cd2662c261a9
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2022/12/msg00013.html
Json schema Security Information SECURITY
https://security.netapp.com/advisory/ntap-20250117-0004

Frequently Asked Questions

What is CVE-2021-3918?
CVE-2021-3918 is a security vulnerability in Json schema involving json-schema is vulnerable to Prototype Pollution under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Json schema versions are affected?
Affected versions include releases prior to 0.4.0 across affected packages: json-schema.
What version fixes CVE-2021-3918?
Upgrading to 0.4.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is json-schema affected?
Yes, json-schema is affected in releases prior to 0.4.0. Upgrade your dependency to 0.4.0 or later.
What is the CVSS score of CVE-2021-3918?
CVE-2021-3918 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-2021-3918?
CVE-2021-3918 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-2021-3918?
Run the dependency tree command: 'npm ls json-schema'. 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-896r-f27r-55mw",
  "modified" : "2025-01-17T21:31:38Z",
  "published" : "2021-11-19T20:16:17Z",
  "aliases" : [ "CVE-2021-3918" ],
  "summary" : "json-schema is vulnerable to Prototype Pollution",
  "details" : "json-schema before version 0.4.0 is vulnerable to Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').",
  "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" : "json-schema"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.4.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-3918"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kriszyp/json-schema/commit/22f146111f541d9737e832823699ad3528ca7741"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kriszyp/json-schema/commit/b62f1da1ff5442f23443d6be6a92d00e65cba93a"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kriszyp/json-schema/commit/f6f6a3b02d667aa4ba2d5d50cc19208c4462abfa"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/kriszyp/json-schema"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.dev/bounties/bb6ccd63-f505-4e3a-b55f-cd2662c261a9"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2022/12/msg00013.html"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20250117-0004"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321", "CWE-915" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-11-15T22:44:27Z",
    "nvd_published_at" : "2021-11-13T09:15:00Z"
  }
}