CVE-2026-26021
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 · uneditedset-in provides the set value of nested associative structure given array of keys. A prototype pollution vulnerability exists in the the npm package set-in (>=2.0.1, < 2.0.5). Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input contained a forbidden key, it is still possible to pollute Object.prototype via a crafted input using Array.prototype. This has been fixed in version 2.0.5.
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 · moderate confidenceThe set-in npm package (versions 2.0.1 through 2.0.4) contains a prototype pollution vulnerability where attackers can pollute Object.prototype via crafted input using Array.prototype methods, bypassing an earlier fix that attempted to block forbidden keys. This allows injection of arbitrary properties into all JavaScript objects.
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>= 2.0.1, < 2.0.5CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 set-in in your project dependenciesSearch your package.json files (including package-lock.json and node_modules/set-in/package.json) for "set-in" in the dependencies, devDependencies, or resolutions sectionsAffected if set-in is listed as a dependency with a version >=2.0.1 and <2.0.5
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Verify the installed version of set-inRun `npm list set-in` or inspect the version field in node_modules/set-in/package.jsonAffected if The installed version is 2.0.1, 2.0.2, 2.0.3, or 2.0.4 (any version >=2.0.1 but <2.0.5)
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Identify code paths that pass user input to set-inSearch your codebase for calls to the set-in function where the second or third argument could be influenced by external input (user data, API requests, config files)Affected if Your code passes unsanitized external input as the path argument to set-in, allowing an attacker to craft an array-based path that reaches Object.prototype
You are affected if set-in version 2.0.1 through 2.0.4 is installed AND your application passes user-controlled input as the path argument to the set-in function.
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 · scoped2.0.5
Upgrade set-in to version 2.0.5 or later to apply the patch that prevents prototype pollution attacks.
2.0.5 or later
- Upgrade the set-in package to version 2.0.5 or later
- Run existing tests to verify the upgrade does not break functionality
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-26021 — 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-2026-26021 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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- Version or environment caveats, and links to real fixes
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