Node.jsApplication
CVE-2023-30581
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 · uneditedThe use of __proto__ in process.mainModule.__proto__.require() can bypass the policy mechanism and require modules outside of the policy.json definition. This vulnerability affects all users using the experimental policy mechanism in all active release lines: v16, v18 and, v20. Please note that at the time this CVE was issued, the policy is an experimental feature of Node.js
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 experimental Node.js policy mechanism, designed to restrict module loading via policy.json, can be bypassed by using __proto__ in the require path (process.mainModule.__proto__.require()). This prototype pollution technique evades policy checks that only validate direct require() calls, allowing unauthorized module loading.
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
Node.jsApplication
>= 16.0.0, < 16.20.1>= 18.0.0, < 18.16.1>= 20.0.0, < 20.3.1CVSS 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
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
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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Check Node.js versionRun `node --version` to determine the installed Node.js versionAffected if The version is >= 16.0.0 and < 16.20.1, OR >= 18.0.0 and < 18.16.1, OR >= 20.0.0 and < 20.3.1
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Verify if policy mechanism is enabledLook for a policy.json file in the project root or check if Node.js is launched with the --experimental-policy flag (e.g., `node --experimental-policy=policy.json app.js`)Affected if A policy.json file exists and is being loaded by Node.js at runtime
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Inspect application code for prototype pollution patternsSearch source code for uses of `process.mainModule.__proto__.require()` or any require() call involving `__proto__` in the pathAffected if The application code contains require calls accessed through __proto__ that could bypass policy restrictions
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Review require() call sourcesAudit all require() calls in the codebase to see if any are invoked via prototype properties rather than direct invocationAffected if Any require() is invoked through a prototype chain (such as obj.require() where obj inherits from Object.prototype) rather than as a direct function call
You are affected if you are running a vulnerable Node.js version (16.x < 16.20.1, 18.x < 18.16.1, or 20.x < 20.3.1) AND have the experimental policy mechanism enabled with a policy.json file, and your application code contains require calls that could leverage __proto__ or prototype chains to bypass policy checks.
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 · scoped16.20.118.16.120.3.1
Avoid using the experimental policy mechanism in production until an official Node.js patch is available; if currently deployed, assess whether the bypass is exploitable in your environment.
Node.js 16.20.1, 18.16.1, or 20.3.1 (depending on your current major version line)
- Check your current Node.js version by running: node --version
- Determine which major version line (16, 18, or 20) you are currently using
- Upgrade Node.js to version 16.20.1 (if using v16), 18.16.1 (if using v18), or 20.3.1 (if using v20) using your preferred package manager (nvm, n, or direct download)
- Verify the upgrade was successful by running: node --version
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Node.js
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-30581 — 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-2023-30581 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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