Vulnerabilities in pkg:npm/flat

PACKAGE
Advisory Identifier: GHSA-2j2x-2gpw-g8fm
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Advisory Summary

CVE-2020-36632 is a CRITICAL (CVSS 9.8) flat vulnerable to prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Flat libraries in the npm ecosystem. The issue involves flat vulnerable to prototype pollution. Remediation is available by upgrading affected packages to version 1.6.2, 2.0.2, 3.0.1, 4.0.2, 5.0.1.

1 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/flat

1 Known Advisory Record(s)

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

Advisory ID CVE / NVD Severity Summary
GHSA-2j2x-2gpw-g8fm CVE-2020-36632 CRITICAL flat vulnerable to Prototype Pollution

CVE-2020-36632 at a Glance

CVE Identifier CVE-2020-36632
GHSA Identifier GHSA-2j2x-2gpw-g8fm
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Flat
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-2020-36632

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

flat fixed: 1.6.2 
npm install flat@1.6.2
flat fixed: 2.0.2 
npm install flat@2.0.2
flat fixed: 3.0.1 
npm install flat@3.0.1
flat fixed: 4.0.2 
npm install flat@4.0.2
flat fixed: 5.0.1 
npm install flat@5.0.1
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 flat

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-36632, inspect your project dependencies using npm:

npm ls flat

Analyze the terminal output to locate any version of Flat in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.6.2), your application is affected.

Note: The npm ls flat 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 Flat, 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

flat helps flatten/unflatten nested Javascript objects. A vulnerability, which was classified as critical, was found in hughsk flat up to 5.0.0. This affects the function unflatten of the file index.js. The manipulation leads to improperly controlled modification of object prototype attributes ('prototype pollution'). It is possible to initiate the attack remotely. Upgrading to version 5.0.1 can address this issue. The name of the patch is 20ef0ef55dfa028caddaedbcb33efbdb04d18e13. It is recommended to upgrade the affected component. The identifier VDB-216777 was assigned to this vulnerability.

CVE-2020-36632 Affected Flat Versions

5 component(s)
Fixed Versions:
1.6.22.0.23.0.14.0.25.0.1
Product / Package Ecosystem Affected Versions Fixed Version
flat
npm/flat
npm
< 1.6.2
1.6.2
flat
npm/flat
npm
≥ 2.0.0
< 2.0.2
2.0.2
flat
npm/flat
npm
≥ 3.0.0
< 3.0.1
All 1 versions
3.0.0
3.0.1
flat
npm/flat
npm
≥ 4.0.0
< 4.0.2
4.0.2
flat
npm/flat
npm
≥ 5.0.0
< 5.0.1
All 1 versions
5.0.0
5.0.1

References

NVD — CVE-2020-36632 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-36632
Flat Source Repository REPOSITORY
https://github.com/hughsk/flat/issues/105
Flat Source Repository REPOSITORY
https://github.com/hughsk/flat/pull/106
Security Fix Commit FIX COMMIT
https://github.com/hughsk/flat/commit/20ef0ef55dfa028caddaedbcb33efbdb04d18e13
Flat Source Repository REPOSITORY
https://github.com/hughsk/flat
Flat Source Repository REPOSITORY
https://github.com/hughsk/flat/compare/3.0.0...3.0.1
Flat Source Repository REPOSITORY
https://github.com/hughsk/flat/compare/4.1.0...4.1.1
Flat Source Repository REPOSITORY
https://github.com/hughsk/flat/compare/v1.6.0...1.6.2
Flat Source Repository REPOSITORY
https://github.com/hughsk/flat/compare/v2.0.1...2.0.2
Flat Release RELEASE
https://github.com/hughsk/flat/releases/tag/5.0.1
vuldb.com/ WEB
https://vuldb.com/?ctiid.216777
vuldb.com/ WEB
https://vuldb.com/?id.216777

Frequently Asked Questions

What is CVE-2020-36632?
CVE-2020-36632 is a security vulnerability in Flat involving flat vulnerable to Prototype Pollution under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Flat versions are affected?
Affected versions include releases prior to 1.6.2, 2.0.2, 3.0.1, 4.0.2, 5.0.1 across affected packages: flat.
What version fixes CVE-2020-36632?
Upgrading to 1.6.2, 2.0.2, 3.0.1, 4.0.2, 5.0.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is flat affected?
Yes, flat is affected in releases prior to 1.6.2, 2.0.2, 3.0.1, 4.0.2, 5.0.1. Upgrade your dependency to 1.6.2, 2.0.2, 3.0.1, 4.0.2, 5.0.1 or later.
What is the CVSS score of CVE-2020-36632?
CVE-2020-36632 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-2020-36632?
CVE-2020-36632 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-2020-36632?
Run the dependency tree command: 'npm ls flat'. 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-2j2x-2gpw-g8fm",
  "modified" : "2026-01-21T14:45:10Z",
  "published" : "2022-12-25T21:30:22Z",
  "aliases" : [ "CVE-2020-36632" ],
  "summary" : "flat vulnerable to Prototype Pollution",
  "details" : "flat helps flatten/unflatten nested Javascript objects. A vulnerability, which was classified as critical, was found in hughsk flat up to 5.0.0. This affects the function unflatten of the file index.js. The manipulation leads to improperly controlled modification of object prototype attributes ('prototype pollution'). It is possible to initiate the attack remotely. Upgrading to version 5.0.1 can address this issue. The name of the patch is 20ef0ef55dfa028caddaedbcb33efbdb04d18e13. It is recommended to upgrade the affected component. The identifier VDB-216777 was assigned to this vulnerability.",
  "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" : "flat"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.6.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "flat"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.0.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "flat"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.0.0"
      }, {
        "fixed" : "3.0.1"
      } ]
    } ],
    "versions" : [ "3.0.0" ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "flat"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.0.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "flat"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0"
      }, {
        "fixed" : "5.0.1"
      } ]
    } ],
    "versions" : [ "5.0.0" ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-36632"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hughsk/flat/issues/105"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hughsk/flat/pull/106"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hughsk/flat/commit/20ef0ef55dfa028caddaedbcb33efbdb04d18e13"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/hughsk/flat"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hughsk/flat/compare/3.0.0...3.0.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hughsk/flat/compare/4.1.0...4.1.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hughsk/flat/compare/v1.6.0...1.6.2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hughsk/flat/compare/v2.0.1...2.0.2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hughsk/flat/releases/tag/5.0.1"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/?ctiid.216777"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/?id.216777"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-12-30T16:27:14Z",
    "nvd_published_at" : "2022-12-25T20:15:00Z"
  }
}