Vulnerability-Lookup

GHSA-WC9G-MQFW-JRWM

Vulnerability from github – Published: 2026-09-08 21:30 – Updated: 2026-09-08 21:30

Summary

multer vulnerable to Denial of Service via crafted multipart field names

Details

Impact

A vulnerability in multer allows a remote, unauthenticated attacker to crash the Node.js process with a single multipart/form-data request. Two specially crafted text field names cause an uncaught RangeError: Invalid array length inside multer's field parsing, which is not routed to the application error handler and terminates the process. All applications using multer to parse multipart requests are affected.

Patches

Users should upgrade to 2.3.0.

Workarounds

None.

Severity

7.5 (High)


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

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JSON

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{
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    {
      "package": {
        "ecosystem": "npm",
        "name": "multer"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-77078"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-08T21:30:20Z",
    "nvd_published_at": "2026-08-28T22:16:53Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nA vulnerability in multer allows a remote, unauthenticated attacker to crash the Node.js process with a single `multipart/form-data` request. Two specially crafted text field names cause an uncaught `RangeError: Invalid array length` inside multer\u0027s field parsing, which is not routed to the application error handler and terminates the process. All applications using multer to parse multipart requests are affected.\n\n### Patches\n\nUsers should upgrade to `2.3.0`.\n\n### Workarounds\n\nNone.",
  "id": "GHSA-wc9g-mqfw-jrwm",
  "modified": "2026-09-08T21:30:21Z",
  "published": "2026-09-08T21:30:20Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/multer/security/advisories/GHSA-wc9g-mqfw-jrwm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77078"
    },
    {
      "type": "WEB",
      "url": "https://github.com/expressjs/multer/commit/87a584e8c8d4da873292635fa1d8c4d78d985b76"
    },
    {
      "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "multer vulnerable to Denial of Service via crafted multipart field names"
}

CVE-2026-77078 (GCVE-0-2026-77078)

Vulnerability from cvelistv5 – Published: 2026-08-28 20:03 – Updated: 2026-08-31 18:40

Title

multer vulnerable to Denial of Service via crafted multipart field names

Summary

multer is a middleware for handling multipart/form-data in Node.js. A small multipart request containing two specially crafted text field names can cause an uncaught RangeError (Invalid array length) that terminates the Node.js process. The first field uses a very large numeric array index to allocate a maximum-length sparse array, and a second field then pushes past that length, which throws inside the append-field dependency and is not caught by multer. All versions before 2.3.0 are affected, and the issue is a remotely triggerable denial of service. The issue is fixed in multer 2.3.0. Upgrade to multer 2.3.0 to remediate.

Severity

7.5 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-31 18:40 UTC

CWE

CWE-248 - Uncaught Exception

Assigner

openjs CNA under the redhat root

CNA scorecard C 65/100 over 99 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/expressjs/multer/security/advi…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
multer	multer	Affected: 0 , < 2.3.0 (semver) Unaffected: 2.3.0 (semver)

Credits

O4FDev UlisesGascon

Show details on NVD website

JSON

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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