CVE-2025-55346
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 · uneditedUser-controlled input flows to an unsafe implementation of a dynamic Function constructor, allowing network attackers to run arbitrary unsandboxed JS code in the context of the host, by sending a simple POST request.
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 confidenceUser-controlled input flows directly to JavaScript's dynamic Function constructor without sanitization, allowing remote attackers to execute arbitrary unsandboxed JavaScript code in the host context via a simple POST request.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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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Identify unsafe Function constructor usageSearch source code for patterns: new Function( or Function( being called with variables that could originate from HTTP request body, query parameters, or headers. Use grep or IDE search for 'new Function' and 'Function(' across the codebase.Affected if Code contains dynamic Function constructor calls where request data (req.body, req.query, req.params, or similar) is passed as arguments without sanitization.
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Trace data flow from HTTP POST to Function constructorExamine the application entry points and middleware. Identify if req.body, req.params, or req.query values are directly assigned to variables that are subsequently passed to Function() or new Function(). Review route handlers handling POST requests.Affected if POST request body fields or URL parameters flow directly into a Function constructor without validation, filtering, or type checking.
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Check for input validation before dynamic code executionReview the code paths leading to the Function constructor call. Look for any input validation, type checking, whitelisting, or sanitization logic that precedes the constructor call. Confirm whether user-controlled input is filtered.Affected if No validation, sanitization, or type checking exists on data reaching the Function constructor, or the validation can be bypassed.
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Identify affected endpoints and HTTP methodsList all route handlers that accept POST requests and contain the vulnerable Function constructor pattern. Note the route paths and request parameter names used.Affected if Any active route handler processes POST requests and passes request data to an unsandboxed Function constructor.
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Review application logs for exploitation attemptsSearch web server and application logs for suspicious patterns such as 'Function(', 'eval(', unusual payload strings in POST requests, or errors indicating failed code injection attempts.Affected if Logs show recent or historical requests with malicious payloads targeting the Function constructor, or unexpected syntax errors in log entries.
Your environment is affected if your application code passes HTTP POST request body, parameters, or headers directly to JavaScript's dynamic Function constructor without sanitization, allowing unauthenticated attackers to execute arbitrary code.
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.
From vendor dataReplace or remove unsafe dynamic Function constructor usage; implement strict allowlist input validation if dynamic code generation is genuinely required, otherwise use safe parameterized alternatives.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-55346 — 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-2025-55346 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