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.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | multer | < 2.3.0 | 2.3.0 |
References
- https://github.com/expressjs/multer/security/advisories/GHSA-wc9g-mqfw-jrwm
- https://nvd.nist.gov/vuln/detail/CVE-2026-77078
- https://github.com/expressjs/multer/commit/87a584e8c8d4da873292635fa1d8c4d78d985b76
- https://cna.openjsf.org/security-advisories.html
- https://github.com/expressjs/multer
- https://github.com/expressjs/multer/releases/tag/v2.3.0
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-248- Platform
- npm
- Package
multer- Disclosed
- 08.09.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-wc9g-mqfw-jrwm - CC BY 4.0
Vulnerability history: multer
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 14
- First → latest
- 05.2025 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 11
- Medium 2
- Low 1
Disclosures per year
- 2025: 4
- 2026: 10
-
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