What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-01 · updated 2026-07-22
• Weakness: CWE-1321

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

• milamer parse-nested-form-data: before 1.0.1

References

• https://github.com/milamer/parse-nested-form-data/commit/527ad58eb486e32438f7198fb88315c20449d792
• https://github.com/milamer/parse-nested-form-data/releases/tag/v1.0.1
• https://github.com/milamer/parse-nested-form-data/security/advisories/GHSA-xp7r-j8r6-j9h3
• https://github.com/milamer/parse-nested-form-data/security/advisories/GHSA-xp7r-j8r6-j9h3

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