{"id":"CVE-2026-82333","aliases":["GHSA-535w-7cp7-47q4"],"url":"https://o3.security/vulnerability/CVE-2026-82333","summary":"multer vulnerable to Denial of Service via oversized array index in field names","details":"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.","published":"2026-08-28T20:12:21.355Z","modified":"2026-09-05T03:48:26.170085686Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"multer","fixedVersion":"2.3.0"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82333.json"},{"type":"ADVISORY","url":"https://github.com/expressjs/multer/security/advisories/GHSA-535w-7cp7-47q4"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-82333"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-05T03:48:26.170085686Z"}}