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CVE-2020-36632: flat vulnerable to Prototype Pollution

December 25, 2022 (updated January 21, 2026)

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.

References

  • github.com/advisories/GHSA-2j2x-2gpw-g8fm
  • github.com/hughsk/flat
  • github.com/hughsk/flat/commit/20ef0ef55dfa028caddaedbcb33efbdb04d18e13
  • github.com/hughsk/flat/compare/3.0.0...3.0.1
  • github.com/hughsk/flat/compare/4.1.0...4.1.1
  • github.com/hughsk/flat/compare/v1.6.0...1.6.2
  • github.com/hughsk/flat/compare/v2.0.1...2.0.2
  • github.com/hughsk/flat/issues/105
  • github.com/hughsk/flat/pull/106
  • github.com/hughsk/flat/releases/tag/5.0.1
  • nvd.nist.gov/vuln/detail/CVE-2020-36632
  • vuldb.com/?ctiid.216777
  • vuldb.com/?id.216777

Code Behaviors & Features

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Affected versions

All versions before 1.6.2, all versions starting from 2.0.0 before 2.0.2, all versions starting from 3.0.0 before 3.0.1, version 3.0.0, all versions starting from 4.0.0 before 4.0.2, all versions starting from 5.0.0 before 5.0.1, version 5.0.0

Fixed versions

  • 1.6.2
  • 2.0.2
  • 3.0.1
  • 4.0.2
  • 5.0.1

Solution

Upgrade to versions 1.6.2, 2.0.2, 3.0.1, 4.0.2, 5.0.1 or above.

Impact 9.8 CRITICAL

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

Learn more about CVSS

Weakness

  • CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Source file

npm/flat/CVE-2020-36632.yml

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