milamer parse-nested-form-data up to 1.0.0 parseFormData names prototype pollution

Summaryinfo

A vulnerability described as critical has been identified in milamer parse-nested-form-data up to 1.0.0. This impacts the function parseFormData. Executing a manipulation of the argument names can lead to prototype pollution. This vulnerability is registered as CVE-2026-45302. It is possible to launch the attack remotely. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical was found in milamer parse-nested-form-data up to 1.0.0. This vulnerability affects the function parseFormData. The manipulation of the argument names with an unknown input leads to a prototype pollution vulnerability. The CWE definition for the vulnerability is CWE-1321. The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. As an impact it is known to affect integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-45302 since 05/11/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059 by the MITRE ATT&CK project.

Upgrading to version 1.0.1 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 527ad58eb486e32438f7198fb88315c20449d792 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• milamer

Name

• parse-nested-form-data

Version

• 1.0

License

• open-source

Website

• Product: https://github.com/milamer/parse-nested-form-data/

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