CVE-2021-23449
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThis affects the package vm2 before 3.9.4 via a Prototype Pollution attack vector, which can lead to execution of arbitrary code on the host machine.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe vm2 library before version 3.9.4 contains a Prototype Pollution vulnerability that allows attackers to modify JavaScript object prototypes. This flaw enables a sandbox escape, granting the attacker the ability to execute arbitrary code on the host machine outside the intended vm2 sandbox isolation.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 3.9.4CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Locate vm2 in your project dependenciesSearch your package.json, package-lock.json, or yarn.lock files for 'vm2' entries, or check if vm2 exists in node_modules/vm2/package.jsonAffected if vm2 is listed as a dependency or exists in node_modules
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Identify the installed vm2 versionRun 'npm list vm2' or 'yarn list vm2' to see the resolved version, or read the version field from node_modules/vm2/package.jsonAffected if The version shown is lower than 3.9.4 (e.g., 3.9.3, 3.9.2, etc.)
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Verify vm2 is actively used in your codeSearch your codebase for require('vm2') or import statements referencing vm2, and review where vm2 is instantiated (e.g., new VM() or similar calls)Affected if Your application code imports and uses vm2 to run untrusted code
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Check for code paths that pass user input to vm2Review the vm2 usage sites found above and trace whether any request parameters, user-uploaded content, or external data flow into the vm2 execution contextAffected if User-controlled input can reach vm2 without sanitization
You are affected if vm2 version 3.9.4 or higher is not installed AND your code actively uses vm2 to execute untrusted input.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.9.4
Upgrade vm2 to version 3.9.4 or later to patch the Prototype Pollution vulnerability; review all code paths where vm2 is used to ensure no malicious input can trigger the flaw before the upgrade is deployed.
vm2 version 3.9.4 or latest stable (3.9.x series)
- Check the current version of vm2 installed in your project using 'npm list vm2' or 'yarn list vm2'
- Upgrade vm2 to version 3.9.4 or later by running 'npm install vm2@^3.9.4' or 'yarn add vm2@^3.9.4'
- Run 'npm install' or 'yarn' to ensure the dependency is properly updated
- Verify the upgrade was successful by checking 'npm list vm2' or 'yarn list vm2'
- Test your application to ensure functionality remains intact after the upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-23449 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-23449 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data