multer is a middleware for handling multipart/form-data in Node.js. A small multipart request with two specially crafted text field names can make multer's field parser synchronously iterate a maximum-length sparse array, blocking the event loop so the process cannot handle other requests. A large numeric array index in the first field allocates a maximum-length sparse array, and a second field with a non-numeric key then triggers a full-length iteration inside the append-field dependency. All versions before 2.3.0 are affected, and this is a remotely triggerable denial of service. multer 2.3.0 adds an opt-in fieldArrayIndexLimit option that rejects oversized array indexes. Upgrade to multer 2.3.0 and set limits.fieldArrayIndexLimit to the largest array index your application needs to remediate.
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History
Fri, 28 Aug 2026 22:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | multer is a middleware for handling multipart/form-data in Node.js. A small multipart request with two specially crafted text field names can make multer's field parser synchronously iterate a maximum-length sparse array, blocking the event loop so the process cannot handle other requests. A large numeric array index in the first field allocates a maximum-length sparse array, and a second field with a non-numeric key then triggers a full-length iteration inside the append-field dependency. All versions before 2.3.0 are affected, and this is a remotely triggerable denial of service. multer 2.3.0 adds an opt-in fieldArrayIndexLimit option that rejects oversized array indexes. Upgrade to multer 2.3.0 and set limits.fieldArrayIndexLimit to the largest array index your application needs to remediate. | |
| Title | multer vulnerable to Denial of Service via oversized array index in field names | |
| Weaknesses | CWE-400 | |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-08-28T20:12:21.355Z
Reserved: 2026-08-28T15:22:56.556Z
Link: CVE-2026-82333
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Status : Received
Published: 2026-08-28T22:16:57.037
Modified: 2026-08-28T22:16:57.037
Link: CVE-2026-82333
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OpenCVE Enrichment
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Weaknesses