CVE-2018-3722: merge-deep node module before 3.0.1 suffers from a Modification of Assumed-Immutable Data (MAID) vulnerability

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HIGH 8.8UPGRADE

CVE-2018-3722 is a high-severity flaw (CVSS 8.8) affecting merge-deep. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	2.0% (top 19%)
CISA exploited list	No
Weakness	CWE-471
Published	2018-06-07
Last modified	2026-06-17

Publisher (CNA): HackerOne · Vendor: merge-deep project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-06-07 02:29 UTCPublished CVE record published
2026-06-17 01:57 UTCUpdated Record last modified

merge-deep project merge-deep UPGRADE

Affected: < 3.0.1

Fixed in: 3.0.1

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls merge-deep

2. UPGRADE to 3.0.1

npm install merge-deep@">=3.0.1"

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2018-3722?

merge-deep: upgrade to 3.0.1. Exact commands for each OS are on this page.

Is CVE-2018-3722 being exploited?

CVE-2018-3722 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-3722 affect?

CVE-2018-3722 affects merge-deep. Severity is high (CVSS 8.8). 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 exis

How urgent is CVE-2018-3722?

Priority 56/100. High severity; Public exploit reference

Related CVEs

CVE-2021-26707 CRITICAL 9.8 UPGRADE MITIGATE The merge-deep library before 3.0.3 for Node.js can be tricked into overwriting properties of Object.prototype

References

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