CVE-2026-30226
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 · uneditedSvelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In devalue v5.6.3 and earlier, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exploitation could lead to Denial of Service (DoS) or type confusion. This vulnerability is fixed in 5.6.4.
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 devalue JavaScript library versions 5.6.3 and earlier contains a prototype pollution vulnerability in the devalue.parse and devalue.unflatten functions. Maliciously crafted payloads can manipulate the JavaScript prototype chain, leading to denial of service or type confusion attacks.
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< 5.6.4CVSS 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
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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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Identify the installed devalue versionRun 'npm list devalue' in your project directory, or inspect the package.json dependencies entry for devalue and its version numberAffected if The version listed is 5.6.3 or earlier
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Locate usage of devalue.parseSearch your codebase for occurrences of 'devalue.parse' or 'parse(' within files that import devalueAffected if The function is called in your code with data from untrusted sources such as user input, API responses, or file uploads
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Locate usage of devalue.unflattenSearch your codebase for occurrences of 'devalue.unflatten' or 'unflatten(' within files that import devalueAffected if The function is called in your code with data from untrusted sources such as user input, API responses, or file uploads
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Inspect data flow to vulnerable functionsReview how data reaches devalue.parse or devalue.unflatten by tracing variables back to their source (query parameters, request bodies, file reads, external APIs)Affected if Untrusted or user-controlled data flows directly to either function without sanitization
You are affected if your project uses devalue version 5.6.3 or earlier and passes untrusted input to devalue.parse or devalue.unflatten functions.
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 · scoped5.6.4
Upgrade devalue to version 5.6.4 or later to remediate this vulnerability.
5.6.4
- Run `npm install [email protected]` to update the devalue package to the fixed version
- Verify the installed version by running `npm list devalue` or checking package.json
- If using a package lock file, run `npm install` to ensure the lock file is updated with the fixed version
- Rebuild and redeploy your application to incorporate the patched library
- Test that devalue.parse and devalue.unflatten functionality still works correctly after the upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 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 $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-30226 — 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-2026-30226 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
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