Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Expressjs | Multer | < 2.3.0 |
Related Weaknesses (CWE)
References
- https://cna.openjsf.org/security-advisories.htmlVendor Advisory
- https://github.com/expressjs/multer/security/advisories/GHSA-535w-7cp7-47q4Vendor Advisory
FAQ
What is CVE-2026-82333?
CVE-2026-82333 is a vulnerability with a CVSS score of 7.5 (HIGH). 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...
How severe is CVE-2026-82333?
CVE-2026-82333 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-82333?
Check the references section above for vendor advisories and patch information. Affected products include: Expressjs Multer.