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Fencer Vulns
medium 6.3

CVE-2020-36632 json

hughsk flat index.js unflatten prototype pollution

published 2022-12-25 3 y ago modified 2026-06-17 4 mo ago also GHSA-2j2x-2gpw-g8fm , EUVD-2022-7475

cvss
6.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
0
none known

Summary

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 is able to 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.

Patch / fix

  • npm flat 1.6.2, 2.0.2, 3.0.1, 4.0.2, 5.0.1
  • flat_project flat 5.0.1

Exploit prediction

1.20% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CNA 3.0 6.3 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
npm flat
<1.6.2
>=2.0.0, <2.0.2
>=3.0.0, <3.0.1
>=4.0.0, <4.0.2
>=5.0.0, <5.0.1
1.6.2
2.0.2
3.0.1
4.0.2
5.0.1

Affected products

  • hughsk flat

Classification

Weakness
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.