multer vulnerable to Denial of Service via file descriptor leak on aborted uploads

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-77037: 0.46% estimated exploitation activity in the next 30 days; percentile 39.68 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A vulnerability in multer 2.2.0 allows an attacker to trigger a Denial of Service (DoS) by aborting or truncating multipart uploads. When using diskStorage, the destination write stream is not closed if the upload is aborted before it finishes, so each failed request leaks an open file descriptor and retains its disk blocks until the process exits. Repeated failed uploads can exhaust the available file descriptors. All applications using multer's disk storage are affected. Patches Users should upgrade to 2.3.0. Workarounds None.

Published by the source

8 Sep 2026, 21:29 UTC

Last modified by the source

8 Sep 2026, 21:45 UTC

Source last checked

26 Oct 2026, 13:02 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-qfvm-cv95-jqjf

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-qfvm-cv95-jqjf

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-qfvm-cv95-jqjf

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# Patch Next advisory brief: CVE-2026-77037

Advisory: multer vulnerable to Denial of Service via file descriptor leak on aborted uploads
IDs: CVE-2026-77037, GHSA-qfvm-cv95-jqjf
Record: https://patchnext.com/advisories/cve-2026-77037 (revision 3, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: multer 2.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm multer: affected >= 2.2.0, <= 2.2.0; fixed in 2.3.0

## Suggested inspection (read-only)
- `npm ls multer --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on multer.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-qfvm-cv95-jqjf (GitHub-reviewed advisory GHSA-qfvm-cv95-jqjf lists affected ranges: npm multer >=2.2.0 <=2.2.0)
- Verified: https://osv.dev/vulnerability/GHSA-qfvm-cv95-jqjf (OSV record GHSA-qfvm-cv95-jqjf lists affected ranges: npm multer >=2.2.0 <2.3.0 (fixed))

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