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OpenAdvisories
High · 8.2 CVE-2026-45302 EUVD-2026-33723GHSA-xp7r-j8r6-j9h3

Prototype Pollution in parse-nested-form-data via `__proto__` in FormData field names

Published Jun 1, 2026 · Updated Jun 2, 2026 · Assigned by GitHub_M

Description

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.

Affected products

VendorProductAffectedFixed
milamer parse-nested-form-data < 1.0.1 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm parse-nested-form-data < 1.0.1 1.0.1 GHSA-xp7r-j8r6-j9h3

References