CVE-2020-15366: Ajv Prototype Pollution Vulnerability

MODERATE
Advisory Identifier: GHSA-v88g-cgmw-v5xw
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CVSS 5.6
CWE-1321 CWE-915
Published
Advisory Summary

CVE-2020-15366 is a MODERATE (CVSS 5.6) prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Ajv libraries in the npm ecosystem. The issue involves prototype pollution in ajv. Remediation is available by upgrading affected packages to version 6.12.3.

CVE-2020-15366 at a Glance

CVE Identifier CVE-2020-15366
GHSA Identifier GHSA-v88g-cgmw-v5xw
Severity MODERATE
CVSS v3.1 Base Score 5.6
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Ajv
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.6

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2020-15366

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

ajv fixed: 6.12.3 
npm install ajv@6.12.3
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 ajv

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-15366, inspect your project dependencies using npm:

npm ls ajv

Analyze the terminal output to locate any version of Ajv in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.12.3), your application is affected.

Note: The npm ls ajv 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 Ajv, 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

An issue was discovered in ajv.validate() in Ajv (aka Another JSON Schema Validator) 6.12.2. A carefully crafted JSON schema could be provided that allows execution of other code by prototype pollution. (While untrusted schemas are recommended against, the worst case of an untrusted schema should be a denial of service, not execution of code.)

CVE-2020-15366 Affected Ajv Versions

1 component(s)
Fixed Versions:
6.12.3
Product / Package Ecosystem Affected Versions Fixed Version
ajv
npm/ajv
npm
< 6.12.3
6.12.3

References

NVD — CVE-2020-15366 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-15366
Security Fix Commit FIX COMMIT
https://github.com/ajv-validator/ajv/commit/65b2f7d76b190ac63a0d4e9154c712d7aa37049f
Ajv Source Repository REPOSITORY
https://github.com/ajv-validator/ajv
Ajv Release RELEASE
https://github.com/ajv-validator/ajv/releases/tag/v6.12.3
Ajv Source Repository REPOSITORY
https://github.com/ajv-validator/ajv/tags
hackerone.com/bugs WEB
https://hackerone.com/bugs?subject=user&report_id=894259
Ajv Security Information SECURITY
https://security.netapp.com/advisory/ntap-20240621-0007

Frequently Asked Questions

What is CVE-2020-15366?
CVE-2020-15366 is a security vulnerability in Ajv involving Prototype Pollution in Ajv under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Ajv versions are affected?
Affected versions include releases prior to 6.12.3 across affected packages: ajv.
What version fixes CVE-2020-15366?
Upgrading to 6.12.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is ajv affected?
Yes, ajv is affected in releases prior to 6.12.3. Upgrade your dependency to 6.12.3 or later.
What is the CVSS score of CVE-2020-15366?
CVE-2020-15366 has a CVSS v3.1 base score of 5.6 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.
What CWE is associated with CVE-2020-15366?
CVE-2020-15366 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-2020-15366?
Run the dependency tree command: 'npm ls ajv'. 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-v88g-cgmw-v5xw",
  "modified" : "2024-06-21T21:33:48Z",
  "published" : "2022-02-10T23:30:59Z",
  "aliases" : [ "CVE-2020-15366" ],
  "summary" : "Prototype Pollution in Ajv",
  "details" : "An issue was discovered in ajv.validate() in Ajv (aka Another JSON Schema Validator) 6.12.2. A carefully crafted JSON schema could be provided that allows execution of other code by prototype pollution. (While untrusted schemas are recommended against, the worst case of an untrusted schema should be a denial of service, not execution of code.)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "ajv"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "6.12.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-15366"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ajv-validator/ajv/commit/65b2f7d76b190ac63a0d4e9154c712d7aa37049f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ajv-validator/ajv"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ajv-validator/ajv/releases/tag/v6.12.3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ajv-validator/ajv/tags"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/bugs?subject=user&report_id=894259"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20240621-0007"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321", "CWE-915" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-10T21:23:41Z",
    "nvd_published_at" : "2020-07-15T20:15:00Z"
  }
}