multiparty: Denial of Service via Prototype Pollution leads to Uncaught Exception
Impact
multiparty@4.2.3 and lower versions are vulnerable to denial of service via uncaught exception. By sending a multipart/form-data request with a field name that collides with an inherited Object.prototype property (e.g., __proto__, constructor, toString), the parser invokes .push() on the inherited prototype value rather than an array, throwing a TypeError that propagates as an uncaught exception and crashes the process. Any service accepting multipart uploads via multiparty is affected.
Patches
Users should upgrade to multiparty@4.3.0 or higher.
Workarounds
None.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | multiparty | < 4.3.0 | 4.3.0 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-1321, CWE-248- Platform
- npm
- Package
multiparty- Disclosed
- 18.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-qxch-whhj-8956 - CC BY 4.0
Vulnerability history: multiparty
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
- 3
- First → latest
- 05.2026 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 3
Disclosures per year
- 2026: 3
-
multiparty: Denial of Service via Prototype Pollution leads to Uncaught Exception this entry
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