CVE-2026-3884
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 · uneditedVersions of the package spin.js before 3.0.0 are vulnerable to Cross-site Scripting (XSS) via the spin() function that allows a creation of more than 1 alert for each 'target' element. An attacker would need to set an arbitrary key-value pair on Object.prototype through a crafted URL achieving a prototype pollution first, before being able to execute arbitrary JavaScript in the context of the user's browser.
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 confidencespin.js versions before 3.0.0 are vulnerable to XSS via the spin() function. The attack requires a two-step process: first, prototype pollution via crafted URL parameters sets arbitrary properties on Object.prototype, then this polluted state enables the spin() function to create multiple alert calls per target element, leading to arbitrary JavaScript execution in the user's browser.
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< 3.0.0CVSS 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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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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Locate the spin.js library fileSearch for spin.js in your project directories (e.g., node_modules, vendor, or static assets). Common paths include node_modules/spin.js/, js/spin.js, or similar. Open the file and look for a version string near the top comment or in a version property.Affected if The file exists and contains a version number lower than 3.0.0 (such as 2.x.x, 1.x.x, or no version visible)
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Identify the spin.js versionWithin the spin.js file, search for a version identifier (e.g., "version", "VERSION", or a semver string like "2.7.1"). If no version is found, check the filename or package.json if this is a Node.js project.Affected if The version string shows anything before 3.0.0, such as 2.9.3, 2.7.1, or 1.0.0
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Check if the application processes URL parametersSearch your codebase for usage of URLSearchParams, location.search, $_GET, request.query, or similar methods that parse URL query strings. Look for code that reads parameters from the URL and uses them in the application.Affected if The application reads and uses URL parameters without sanitization, which could enable prototype pollution
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Determine if spin() is called on user-influenced elementsSearch your code for calls to spin(), new Spin(), or similar constructors. Check whether the target element passed to spin() or the options passed to it could be influenced by URL parameters or other user input.Affected if spin() is called with elements or options derived from URL parameters or user input
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Verify prototype pollution is possibleReview how URL parameters are processed. If the application directly assigns URL parameter values to object properties without validation, prototype pollution may be possible. Search for patterns like obj[param] = value or Object.assign(obj, params).Affected if URL parameters are directly assigned to object properties without validation, allowing properties to be set on Object.prototype
You are affected if spin.js version is below 3.0.0 AND your application processes URL parameters that could pollute the prototype AND spin() is called on elements influenced by those parameters.
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 · scoped3.0.0
Upgrade spin.js to version 3.0.0 or later. Additionally, sanitize all URL parameters to prevent prototype pollution attacks.
3.0.0
- Upgrade spin.js to version 3.0.0 or later by updating the dependency in your package.json or package-lock.json file
- Run npm install or yarn install to update the package
- Verify the upgrade by checking the installed version with npm list spin.js or yarn list spin.js
- Test that the spin() function still works correctly in your application
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-2026-3884 — 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-2026-3884 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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