CVE-2026-77078

multer vulnerable to Denial of Service via crafted multipart field names

Published Aug 28, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-wc9g-mqfw-jrwm multer vulnerable to Denial of Service via crafted multipart field names
History
Type Values Removed Values Added
First Time appeared Expressjs
Expressjs multer
CPEs cpe:2.3:a:expressjs:multer:*:*:*:*:*:node.js:*:*
Vendors & Products Expressjs
Expressjs multer
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Multer
Multer multer
Vendors & Products Multer
Multer multer
Type Values Removed Values Added
Description 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.
Title multer vulnerable to Denial of Service via crafted multipart field names
Weaknesses CWE-248
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
openjs
Published
Updated
Aug 31, 2026, 6:40 PM
Reserved
Aug 20, 2026, 10:53 AM
Status
Analyzed
Published
Aug 28, 2026, 10:16 PM
Modified
Sep 2, 2026, 2:46 PM