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CVE-2020-36632 — Vulnerability in flat — CVE Details

CRITICAL

flat vulnerable to Prototype Pollution

Published December 25, 2022Updated February 3, 2026Source: osv

Summary

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.

Advisory Timeline

  • First published December 25, 2022 (1387 days ago).
  • Last revised February 3, 2026 — 1135 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

npm
Update flat to 4.0.2 or later
npm install flat@4.0.2
npm
Update flat to 5.0.1 or later
npm install flat@5.0.1
npm
Update flat to 1.6.2 or later
npm install flat@1.6.2
npm
Update flat to 2.0.2 or later
npm install flat@2.0.2
npm
Update flat to 3.0.1 or later
npm install flat@3.0.1

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (5)

Affects 1 ecosystem: npm (1).

PackageEcosystemAffectedFixed In
flat
npm
All versions4.0.2
flat
npm
5.0.05.0.1
flat
npm
All versions1.6.2
flat
npm
All versions2.0.2
flat
npm
3.0.03.0.1

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

  • CWE-1321
    Prototype PollutionMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 9.8 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Frequently Asked Questions

What is CVE-2020-36632?
flat vulnerable to Prototype Pollution This vulnerability has been assigned a severity rating of CRITICAL (CVSS score: 9.8/10).
How do I check if my project is affected by CVE-2020-36632?
CVE-2020-36632 affects flat. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2020-36632 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
9.8

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-2j2x-2gpw-g8fm

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