CVE-2020-28279: Flattenizer Flattenizer Vulnerable To Prototype Pollution Vulnerability

CRITICAL
Advisory Identifier: GHSA-vq33-26pr-r4h6
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CVSS 9.8
CWE-1321
Published
Advisory Summary

CVE-2020-28279 is a CRITICAL (CVSS 9.8) flattenizer vulnerable to prototype pollution vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Flattenizer libraries in the npm ecosystem. The issue involves flattenizer vulnerable to prototype pollution. Remediation is available by upgrading affected packages to version 1.1.1.

CVE-2020-28279 at a Glance

CVE Identifier CVE-2020-28279
GHSA Identifier GHSA-vq33-26pr-r4h6
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Flattenizer
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-2020-28279

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

flattenizer fixed: 1.1.1 
npm install flattenizer@1.1.1
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 flattenizer

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-28279, inspect your project dependencies using npm:

npm ls flattenizer

Analyze the terminal output to locate any version of Flattenizer in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.1.1), your application is affected.

Note: The npm ls flattenizer 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 Flattenizer, 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

### Overview Prototype pollution vulnerability in ‘flattenizer’ versions 0.0.5 through 1.0.5 allows an attacker to cause a denial of service and may lead to remote code execution. ### Details The NPM module 'flattenizer' can be abused by Prototype Pollution vulnerability since the function 'unflatten()' did not check for the type of object before assigning value to the property. Due to this flaw an attacker could create a non-existent property or able to manipulate the property which leads to Denial of Service or potentially Remote code execution. ### PoC Details There is no validation before assigning the property to check whether the assigned argument is the Object's own property or not, the property `polluted` will be directly be assigned thereby polluting the Object prototype. Later in the code, if there is a check to validate `polluted` the valued would be substituted as "true" as it had been polluted. ```js var flattenizer = require("flattenizer") flattenizer.unflatten({'__proto__.polluted': true}); console.log(polluted); ```

CVE-2020-28279 Affected Flattenizer Versions

1 component(s)
Fixed Versions:
1.1.1
Product / Package Ecosystem Affected Versions Fixed Version
flattenizer
npm/flattenizer
npm
≥ 0.0.5
< 1.1.1
1.1.1

References

NVD — CVE-2020-28279 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-28279
Flattenizer Source Repository REPOSITORY
https://github.com/sahellebusch/flattenizer/pull/13
Security Fix Commit FIX COMMIT
https://github.com/sahellebusch/flattenizer/commit/3c6a6353df7c8879e931973b81a49a47f6c2b399
web.archive.org/web/20210104205035/... WEB
https://web.archive.org/web/20210104205035/https://www.whitesourcesoftware.com/vulnerability-database/CVE-2020-28279

Frequently Asked Questions

What is CVE-2020-28279?
CVE-2020-28279 is a security vulnerability in Flattenizer involving flattenizer vulnerable to prototype pollution under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Flattenizer versions are affected?
Affected versions include releases prior to 1.1.1 across affected packages: flattenizer.
What version fixes CVE-2020-28279?
Upgrading to 1.1.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is flattenizer affected?
Yes, flattenizer is affected in releases prior to 1.1.1. Upgrade your dependency to 1.1.1 or later.
What is the CVSS score of CVE-2020-28279?
CVE-2020-28279 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-2020-28279?
CVE-2020-28279 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-2020-28279?
Run the dependency tree command: 'npm ls flattenizer'. 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-vq33-26pr-r4h6",
  "modified" : "2024-04-01T22:02:50Z",
  "published" : "2022-05-24T17:37:25Z",
  "aliases" : [ "CVE-2020-28279" ],
  "summary" : "flattenizer vulnerable to prototype pollution",
  "details" : "### Overview\nPrototype pollution vulnerability in ‘flattenizer’ versions 0.0.5 through 1.0.5 allows an attacker to cause a denial of service and may lead to remote code execution.\n\n### Details\nThe NPM module 'flattenizer' can be abused by Prototype Pollution vulnerability since the function 'unflatten()' did not check for the type of object before assigning value to the property. Due to this flaw an attacker could create a non-existent property or able to manipulate the property which leads to Denial of Service or potentially Remote code execution.\n\n### PoC Details\nThere is no validation before assigning the property to check whether the assigned argument is the Object's own property or not, the property `polluted` will be directly be assigned thereby polluting the Object prototype. Later in the code, if there is a check to validate `polluted` the valued would be substituted as \"true\" as it had been polluted.\n\n```js\nvar flattenizer = require(\"flattenizer\")\nflattenizer.unflatten({'__proto__.polluted': true});\nconsole.log(polluted);\n```",
  "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" : "flattenizer"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.0.5"
      }, {
        "fixed" : "1.1.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.0.5"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-28279"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sahellebusch/flattenizer/pull/13"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sahellebusch/flattenizer/commit/3c6a6353df7c8879e931973b81a49a47f6c2b399"
  }, {
    "type" : "WEB",
    "url" : "https://web.archive.org/web/20210104205035/https://www.whitesourcesoftware.com/vulnerability-database/CVE-2020-28279"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-04-01T22:02:50Z",
    "nvd_published_at" : "2020-12-29T18:15:00Z"
  }
}