CVE-2026-5038
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 · uneditedImpact: multer versions 2.0.0-alpha.1 through 2.1.1 and 3.0.0-alpha.1 are vulnerable to a Denial of Service when using diskStorage. Aborted or malformed multipart uploads leave orphaned partial files on disk because the Readable.pipe() call does not propagate the stream destroy signal to the underlying fs.WriteStream. An attacker can exhaust disk space by triggering many aborted uploads, with no application bug required. Patches: Users should upgrade to multer 2.2.0 (2.x line) or 3.0.0-alpha.2 (3.x prerelease). Both versions track in-flight write streams and clean them up on the abort path. Workarounds: None.
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 confidencemulter's diskStorage implementation fails to propagate stream destruction signals when multipart uploads are aborted, causing orphaned partial files to remain on disk. The Readable.pipe() call doesn't signal the underlying fs.WriteStream to clean up, allowing attackers to exhaust disk space by triggering many aborted uploads.
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>= 2.0.0, < 2.2.0= 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
- 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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Check installed multer versionRun `npm list multer` in your project directory to see the installed versionAffected if Version is 2.0.0 through 2.1.x, or exactly 3.0.0 (the only affected 3.x version listed)
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Confirm multer diskStorage is in useSearch your codebase for multer configuration using diskStorage or dest options (for example: `multer({ storage: multer.diskStorage(...) })` or `multer({ dest: 'folder' })`)Affected if Your multer setup explicitly configures diskStorage or a destination folder for handling file uploads
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Inspect upload directory for orphaned filesExamine your configured upload or temporary directory for partial files that may remain after upload requests are terminated or abortedAffected if You observe unexpected partial files accumulating without corresponding active or completed upload requests
You are affected if multer version is >= 2.0.0 and < 2.2.0, or exactly 3.0.0, AND your application uses diskStorage to handle multipart uploads, which can lead to orphaned partial files consuming disk space.
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 · scoped2.2.0
Upgrade multer to version 2.2.0 (for 2.x users) or 3.0.0-alpha.2 (for 3.x prerelease users) to resolve the orphaned file cleanup issue.
multer 2.2.0 (or 3.0.0-alpha.2 for 3.x prerelease)
- Check the current multer version in your project's package.json file
- Update the multer dependency version to 2.2.0 (for 2.x line) or 3.0.0-alpha.2 (for 3.x line) in package.json
- Run 'npm install' or 'yarn install' to download and install the fixed version
- Verify the installation was successful by checking the installed multer version
- Test multipart file upload functionality, including aborted and malformed uploads, to confirm the vulnerability is remediated
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-5038 — 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-2026-5038 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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