CVE-2026-46510CWE-1321

Prototype pollution in form-data-objectizer via bracket-notation form keys

High · published May 29, 2026

CVSS v3.1
8.2
EPSS
0%
Percentile
39.2
In the wild
Unconfirmed
What it is

form-data-objectizer converts FormData to object. Prior to 1.0.1, form-data-objectizer walks bracket-notation form keys (e.g. name[sub]) into nested objects without filtering __proto__, constructor, or prototype. A single HTTP form field whose name starts with __proto__[...] causes the library to mutate Object.prototype, which is a prototype pollution primitive of the entire Node.js process. This vulnerability is fixed in 1.0.1.

The record
Technical detail
CVSS v3.1
8.2 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
CVSS v4.0
Not supplied
EPSS
0.00464 · 39.2th percentile
Weakness
CWE-1321 · Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Published
2026-05-29T13:40Z
EPSS history
Timeline
  • 29 MAY 13:40Z
    Prototype pollution in form-data-objectizer via bracket-notation form keys
    cvelistv5