CVE-2026-8161CWE-1321CWE-248

multiparty vulnerable to Denial of Service via Prototype Pollution leading to Uncaught Exception

High · published May 12, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
44.2
In the wild
Unconfirmed
What it is

[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 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 [email protected] or higher.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00533 · 44.2th percentile
Weaknesses
CWE-1321 · Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'); CWE-248 · Uncaught Exception
Published
2026-05-12T08:50Z
EPSS history
Timeline
  • 12 MAY 08:50Z
    multiparty vulnerable to Denial of Service via Prototype Pollution leading to Uncaught Exception
    cvelistv5