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MEDIUM severity

CVE-2021-23397 — @ianwalter/merge

MEDIUM

CVE-2021-23397 is a medium-severity (CVSS 5.6) CWE-1321 vulnerability in @ianwalter/merge. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

@ianwalter/merge Prototype Pollution via `merge` function

Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Oct 30, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.8%probability of exploitation in next 30 days
Lower Risk+0.02%
Lower risk than most CVEs57th percentile — riskier than 57% of all scored CVEsHighest risk
0.00%0.44%0.88%1.32%0.4%0.8%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

12other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
@ianwalter/mergenpm
200downloads / week

Description

All versions of package @ianwalter/merge are vulnerable to Prototype Pollution via the main (merge) function. @ianwalter/merge is deprecated and the maintainer suggests using @generates/merger instead.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npm@ianwalter/mergeall versionsNo fix

Affected Products

1 product · 1 configurations
Application
mergemerge_project
all
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

All versions of package @ianwalter/merge are vulnerable to Prototype Pol…

security.snyk.ioNVDAug 2022

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @ianwalter/merge, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    The records we use list no patched version of @ianwalter/merge for CVE-2021-23397. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

All versions of package @ianwalter/merge are vulnerable to Prototype Pollution via the main (`merge`) function. @ianwalter/merge is [deprecated](https://github.com/ianwalter/merge/blob/master/README.md) and the maintainer suggests using [@generates/merger](https://github.com/generates/generates/tree/main/packages/merger) instead.
O3 Security · Impact-Aware SCA

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CVE-2021-23397: @ianwalter/merge (Medium 5.6)