CVE-2026-45302 HIGH

CVE-2026-45302: Prototype Pollution in parse-nested-form-data via `__proto__` in FormData field names

Vendor Milamer
Product parse-nested-form-data
Weakness CWE-1321
Published June 1, 2026
Last update June 2, 2026

CVSS base score

8.2/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity High

CVSS vector

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

What the vulnerability does

01Description

parse-nested-form-data is a tiny node module for parsing FormData by name into objects and arrays. Prior to version 1.0.1, parseFormData() walks bracket and dot-notation FormData field names into nested objects without filtering reserved property keys. A single FormData field whose name begins with __proto__, or contains .__proto__. mid-path, causes the parser to traverse onto Object.prototype and assign properties there, polluting the prototype chain of every plain object in the running process. This issue has been patched in version 1.0.1.

Key dates

02Disclosure timeline

June 1, 2026 CVE published
June 2, 2026 Record updated