multer vulnerable to Denial of Service via crafted multipart field names
### Impact A vulnerability in multer allows a remote, unauthenticated attacker to crash the Node.js process with a single `multipart/form-data` request. Two specially crafted text field names cause an uncaught `RangeError: Invalid array length` inside multer's field parsing, which is not routed to the application error handler and terminates the process. All applications using multer to parse multipart requests are affected. ### Patches Users should upgrade to `2.3.0`. ### Workarounds None.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-77078US | — | Exploit | ||
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 (In… | ||||
references
External citations — patches, advisories, analysis.
- https://cna.openjsf.org/security-advisories.htmlWEB
- https://github.com/expressjs/multerPACKAGE
- https://github.com/expressjs/multer/commit/87a584e8c8d4da873292635fa1d8c4d78d985b76WEB
- https://github.com/expressjs/multer/releases/tag/v2.3.0WEB
- https://github.com/expressjs/multer/security/advisories/GHSA-wc9g-mqfw-jrwmWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-77078ADVISORY
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