GitHub Advisoryadvisory · npm

GHSA-qxch-whhj-8956 multiparty: Denial of Service via Prototype Pollution leads to Uncaught Exception

HIGH Published 2026-05-18 Modified 2026-05-18 Official page ↗
Aliases
CVE-2026-8161
Ecosystem
npm
Packages
multiparty
Severity
High
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses
CWE-1321, CWE-248
Reviewed
2026-05-18

Affected packages

• npm multiparty: < 4.3.0 → fixed in 4.3.0

Description

Impact [email protected] 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 [email protected] or higher. Workarounds None.

Related

Alias · CVE (1)

Weakness · CWE (2)

  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes weakness
  • CWE-248 Uncaught Exception weakness

References