# CVE-2026-2359: expressjs multer denial of service via resource exhaustion

Source: https://junglewise.ai/threats/cve-2026-2359-expressjs-multer-denial-of-service-via-resource-exhaustion  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-02-27. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-2359 · Severity: high · CVSS 7.5 · Published 2026-02-27

Multer is a popular software component used by web applications to handle file uploads. A security flaw in this component allows an attacker to crash the service or make it unresponsive by repeatedly starting and then abruptly dropping file upload connections. This can lead to a total service outage, preventing legitimate users from accessing the application.

Technologies: [multer (npm)](https://junglewise.ai/threats/technologies/npm-multer). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-2359 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-2359 being exploited in the wild.

**How severe is CVE-2026-2359?** High severity, with a CVSS score of 7.5, published 27 February 2026.

**Which products and versions are affected?** multer (npm) SEMVER:introduced=0,fixed=2.1.0.

**Is there a fix for CVE-2026-2359?** Yes. multer (npm): upgrade to 2.1.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-2359 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-2359?** Check whether you run multer (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- multer (npm): upgrade to 2.1.0 or later

  ```sh
  npm install multer@2.1.0
  ```


## Technical details

A Denial of Service (DoS) vulnerability exists in Multer due to improper handling of aborted connections during multipart/form-data uploads. The root cause is a failure to release system resources (CWE-772) when a client abruptly terminates a connection while a file is being uploaded. An unauthenticated remote attacker can exploit this by initiating multiple concurrent uploads and dropping the connections, leading to resource exhaustion and service unavailability. The issue is addressed in version 2.1.0 by improving disconnect handling and ensuring cleanup of aborted uploads.

## Affected products

- expressjs multer < 2.1.0

## Identifiers

- CVE-2026-2359
- GHSA-v52c-386h-88mc

## Timeline

- 2026-02-27: advisory: Initial advisory published by OpenJS Foundation
- 2026-02-27: patched: Version 2.1.0 released with fix

## References

- [https://cna.openjsf.org/security-advisories.html](https://cna.openjsf.org/security-advisories.html)
- [https://github.com/expressjs/multer/commit/cccf0fe0e64150c4f42ccf6654165c0d66b9adab](https://github.com/expressjs/multer/commit/cccf0fe0e64150c4f42ccf6654165c0d66b9adab)
- [https://github.com/expressjs/multer/security/advisories/GHSA-v52c-386h-88mc](https://github.com/expressjs/multer/security/advisories/GHSA-v52c-386h-88mc)
- [https://www.cve.org/CVERecord?id=CVE-2026-2359](https://www.cve.org/CVERecord?id=CVE-2026-2359)
- [https://access.redhat.com/errata/RHSA-2026:6174](https://access.redhat.com/errata/RHSA-2026:6174)
- [https://access.redhat.com/errata/RHSA-2026:6802](https://access.redhat.com/errata/RHSA-2026:6802)
- [https://access.redhat.com/security/cve/CVE-2026-2359](https://access.redhat.com/security/cve/CVE-2026-2359)

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- [Express multer Denial of Service via orphaned disk writes](https://junglewise.ai/threats/cve-2026-88932-express-multer-denial-of-service-via-orphaned-disk-writes)
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