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CRITICAL severity

CVE-2020-28448 — multi-ini

CRITICALFix: evangelion1204/multi-ini#37

CVE-2020-28448 is a critical-severity (CVSS 9.8) CWE-1321 vulnerability in multi-ini. 2 public exploit references exist, so weaponization risk is real. A fix is available for multi-ini — see the affected versions and patch details below.

Prototype Pollution in multi-ini

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
2 known
Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs73th percentile — riskier than 73% of all scored CVEsHighest risk
0.00%0.65%1.30%1.96%0.4%1.5%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2020-28448 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

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.

13other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
multi-ininpm
2Kdownloads / week

Description

This affects the package multi-ini before 2.1.1. It is possible to pollute an object's prototype by specifying the proto object as part of an array.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmmulti-iniall versions2.1.1npm install multi-ini@2.1.1

Affected Products

1 product · 1 configurations
Application
multi-inimulti-ini_project
< 2.1.1
range
Exploits & PoCs
2

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

This affects the package multi-ini before 2.1.1. It is possible to pollu…

snyk.ioNVDJul 2021

This affects the package multi-ini before 2.1.1. It is possible to pollu…

github.comNVDJul 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update multi-ini to 2.1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-28448 is resolved across your whole dependency graph.

  3. Workarounds

    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

This affects the package multi-ini before 2.1.1. It is possible to pollute an object's prototype by specifying the proto object as part of an array.
O3 Security · Impact-Aware SCA

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CVE-2020-28448: multi-ini — Fixed in 2.1.1