CVE-2026-3304Network attack vector

Service interruption via orphaned upload files

Published Feb 27, 2026 · Updated Feb 27, 2026

Incomplete cleanup in Express.js Multer before 2.1.0 allows remote attackers to exhaust disk resources with malformed multipart uploads. The makeMiddleware fileFilter callback can run after request error handling; it leaves the file placeholder registered and fails to resume the stream, so the uploaded file is not removed. Exploitation requires an upload endpoint using Multer with an asynchronous fileFilter, and repeated requests can fill storage and interrupt the hosting service.

CVSS severity8.7
High
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incomplete cleanup in Express.js Multer before 2.1.0 allows remote attackers to exhaust disk resources with malformed multipart uploads. The makeMiddleware fileFilter callback can run after request error handling; it leaves the file placeholder registered and fails to resume the stream, so the uploaded file is not removed. Exploitation requires an upload endpoint using Multer with an asynchronous fileFilter, and repeated requests can fill storage and interrupt the hosting service.

The record

CVE
CVE-2026-3304
Published
Feb 27, 2026
Updated
Feb 27, 2026
Vendor
body-parser
Product
Multer
Classifications
CWE-459, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.0.0 <2.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

body-parser · Multerversion=0.0.0 <2.1.0

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7OpenJS FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-459Incomplete Cleanup
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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