Multer vulnerable to Denial of Service via unhandled exception

Exploitation

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

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2025-48997: 0.48% estimated exploitation activity in the next 30 days; percentile 41.62 (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 versions =1.4.4-lts.1, <2.0.1 allows an attacker to trigger a Denial of Service (DoS) by sending an upload file request with an empty string field name. This request causes an unhandled exception, leading to a crash of the process. Patches Users should upgrade to 2.0.1 Workarounds None References https://github.com/expressjs/multer/commit/35a3272b611945155e046dd5cef11088587635e9 https://github.com/expressjs/multer/issues/1233 https://github.com/expressjs/multer/pull/1256

Published by the source

5 Jun 2025, 01:09 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:37 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g5hg-p3ph-g8qg

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-g5hg-p3ph-g8qg

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# Patch Next advisory brief: CVE-2025-48997

Advisory: Multer vulnerable to Denial of Service via unhandled exception
IDs: CVE-2025-48997, GHSA-g5hg-p3ph-g8qg
Record: https://patchnext.com/advisories/cve-2025-48997 (revision 3, source checked 26 Oct 2026, 12:37 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: multer 2.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm multer: affected >= 1.4.4-lts.1, < 2.0.1; fixed in 2.0.1

## 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://osv.dev/vulnerability/GHSA-g5hg-p3ph-g8qg (OSV record GHSA-g5hg-p3ph-g8qg lists affected ranges: npm multer >=1.4.4-lts.1 <2.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-g5hg-p3ph-g8qg (GitHub-reviewed advisory GHSA-g5hg-p3ph-g8qg lists affected ranges: npm multer >=1.4.4-lts.1 <2.0.1)

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