CVE-2026-8161 HIGH

CVE-2026-8161: multiparty vulnerable to Denial of Service via Prototype Pollution leading to Uncaught Exception

Vendor Multiparty
Product multiparty
Weakness CWE-248
Published May 12, 2026
Last update May 12, 2026

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

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 such as __proto__, constructor, or 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. Impact: any service accepting multipart uploads via multiparty is affected. Workarounds: none. Upgrade to multiparty@4.3.0 or higher.

Key dates

02Disclosure timeline

May 12, 2026 CVE published
May 12, 2026 Record updated