Skip to content
Fencer Intel
high 8.8

CVE-2018-3722 json

Prototype Pollution in merge-deep

published 2018-06-07 8 y ago modified 2026-06-17 4 mo ago also GHSA-9g9w-hmvj-5h57 , EUVD-2018-0254

cvss
8.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 80%
public exploits
0
none known

Summary

merge-deep node module before 3.0.1 suffers from a Modification of Assumed-Immutable Data (MAID) vulnerability, which allows a malicious user to modify the prototype of "Object" via __proto__, causing the addition or modification of an existing property that will exist on all objects.

Patch / fix

  • npm merge-deep 3.0.1
  • merge-deep_project merge-deep 3.0.1

Exploit prediction

2.00% chance of exploitation in the next 30 days, higher than 80% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/310708 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 8.8 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P
GitHub 3.0 8.8 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
npm merge-deep
<3.0.1
3.0.1

Affected products

  • HackerOne merge-deep node module

Classification

Weakness
  • CWE-471 Modification of Assumed-Immutable Data (MAID)

References

Sources

Fencer Intel 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.