How severe is CVE-2021-23328?

CVE-2021-23328 has a CVSS score of 5.6/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-23328?

CVE-2021-23328 affects the following packages: iniparserjs (npm). Ecosystems affected: npm.

How do I fix CVE-2021-23328?

No patched version of iniparserjs has shipped for CVE-2021-23328 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect CVE-2021-23328 in my npm dependencies?

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

How do I mitigate CVE-2021-23328 if there is no patch (or I can't update yet)?

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.

Is CVE-2021-23328 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-23328, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-23328?

CVE-2021-23328 has an EPSS (Exploit Prediction Scoring System) score of 1.0%, placing it in the 61th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2021-23328 published, and has it been updated?

CVE-2021-23328 was published on April 13, 2021 and was last updated on November 8, 2023. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

CVE-2021-23328 — iniparserjs

MEDIUM

CVE-2021-23328 is a medium-severity (CVSS 5.6) vulnerability in iniparserjs. 1 public exploit reference exists, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

Prototype Pollution in iniparserjs

Published

Apr 13, 2021

Updated

Nov 8, 2023

Affected

1 pkg

Patched

See advisory

Exploits

1 known

Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs61th percentile — riskier than 61% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2021-23328 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 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, a proxy for how much of the ecosystem is exposed.

iniparserjsnpm

34downloads / week

Description

This affects all versions of package iniparserjs. This vulnerability relates when ini_parser.js is concentrating arrays. Depending on if user input is provided, an attacker can overwrite and pollute the object prototype of a program.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
📦npm	`iniparserjs`	all versions	No fix

Affected Products

1 product · 1 configurations

Application

iniparserjsiniparserjs_project

all

Exploits & PoCs

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 all versions of package iniparserjs. This vulnerability rel…

snyk.ioNVDFeb 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for iniparserjs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of iniparserjs has shipped for CVE-2021-23328 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
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

O3 Security · Impact-Aware SCA

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