{"id":"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.","aliases":["GHSA-535w-7cp7-47q4"],"modified":"2026-09-05T03:48:26.170085686Z","published":"2026-08-28T20:12:21.355Z","database_specific":{"cna_assigner":"openjs","cwe_ids":["CWE-400"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82333.json"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/expressjs/multer","events":[{"introduced":"0"},{"fixed":"4e8edf50dbb5ddec213b6253642cbc08ce0225a7"}],"database_specific":{"cpe":"cpe:2.3:a:expressjs:multer:*:*:*:*:*:node.js:*:*","extracted_events":[{"introduced":"0"},{"fixed":"2.3.0"}],"source":["AFFECTED_FIELD","CPE_RANGE"]}}],"versions":["v2.2.0","v2.1.1","v2.1.0","v2.0.2","v2.0.1","v2.0.0","v1.4.5-lts.2","v1.4.5-lts.1","v1.4.4","v1.4.4-lts.1","v1.4.3","v1.4.2","v1.4.1","v1.4.0","v1.3.1","v1.3.0","v1.2.1","v1.2.0","v1.1.0","v1.0.6","v1.0.5","v1.0.4","v1.0.3","v1.0.2","v1.0.1","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-82333.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}