CVE-2020-36632: Flat Flat Vulnerable To Prototype Pollution Vulnerability
CRITICALCVE-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.
CVE-2020-36632 at a Glance
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).
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.
npm install flat@1.6.2npm install flat@2.0.2npm install flat@3.0.1npm install flat@4.0.2npm install flat@5.0.1Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls flatHow 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 flatAnalyze 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
CVE-2020-36632 Affected Flat Versions
5 component(s)References
Frequently Asked Questions
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Machine-readable OSV JSON
OSV v1.5 Schema
{
"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"
}
}