CVE-2026-77037: Multer Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-qfvm-cv95-jqjf
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CVSS 7.5
CWE-400 CWE-459
Published
Advisory Summary

CVE-2026-77037 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Multer libraries in the npm ecosystem. The issue involves multer vulnerable to denial of service via file descriptor leak on aborted uploads. Remediation is available by upgrading affected packages to version 2.3.0.

CVE-2026-77037 at a Glance

CVE Identifier CVE-2026-77037
GHSA Identifier GHSA-qfvm-cv95-jqjf
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Multer
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-77037

To remediate this vulnerability, upgrade all affected Multer dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

multer fixed: 2.3.0 
npm install multer@2.3.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls multer

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-77037, inspect your project dependencies using npm:

npm ls multer

Analyze the terminal output to locate any version of Multer in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.3.0), your application is affected.

Note: The npm ls multer command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In Multer, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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.

CVE-2026-77037 Affected Multer Versions

1 component(s)
Fixed Versions:
2.3.0
Product / Package Ecosystem Affected Versions Fixed Version
multer
npm/multer
npm
≥ 2.2.0
< 2.3.0
All 1 versions
2.2.0
2.3.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/expressjs/multer/security/advisories/GHSA-qfvm-cv95-jqjf
NVD — CVE-2026-77037 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-77037
Security Fix Commit FIX COMMIT
https://github.com/expressjs/multer/commit/eef74440b491ef0f976f3d25895e8089ae495df0
Multer Security Information SECURITY
https://cna.openjsf.org/security-advisories.html
Multer Source Repository REPOSITORY
https://github.com/expressjs/multer
Multer Release RELEASE
https://github.com/expressjs/multer/releases/tag/v2.3.0

Frequently Asked Questions

What is CVE-2026-77037?
CVE-2026-77037 is a security vulnerability in Multer involving multer vulnerable to Denial of Service via file descriptor leak on aborted uploads under CWE-400: Uncontrolled Resource Consumption.
Which Multer versions are affected?
Affected versions include releases prior to 2.3.0 across affected packages: multer.
What version fixes CVE-2026-77037?
Upgrading to 2.3.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is multer affected?
Yes, multer is affected in releases prior to 2.3.0. Upgrade your dependency to 2.3.0 or later.
What is the CVSS score of CVE-2026-77037?
CVE-2026-77037 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-77037?
CVE-2026-77037 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check npm dependencies for CVE-2026-77037?
Run the dependency tree command: 'npm ls multer'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qfvm-cv95-jqjf",
  "modified" : "2026-09-08T21:29:51Z",
  "published" : "2026-09-08T21:29:51Z",
  "aliases" : [ "CVE-2026-77037" ],
  "summary" : "multer vulnerable to Denial of Service via file descriptor leak on aborted uploads",
  "details" : "### Impact\n\nA 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.\n\n### Patches\n\nUsers should upgrade to `2.3.0`.\n\n### Workarounds\n\nNone.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "multer"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.2.0"
      }, {
        "fixed" : "2.3.0"
      } ]
    } ],
    "versions" : [ "2.2.0" ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/expressjs/multer/security/advisories/GHSA-qfvm-cv95-jqjf"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-77037"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/expressjs/multer/commit/eef74440b491ef0f976f3d25895e8089ae495df0"
  }, {
    "type" : "WEB",
    "url" : "https://cna.openjsf.org/security-advisories.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/expressjs/multer"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/expressjs/multer/releases/tag/v2.3.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400", "CWE-459" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-08T21:29:51Z",
    "nvd_published_at" : "2026-08-28T22:16:53Z"
  }
}