CVE-2026-45302 Prototype Pollution in parse-nested-form-data via `__proto__` in FormData field names
Prototype pollution in parse-nested-form-data allows attackers to modify Object.prototype via crafted FormData field names, potentially leading to code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45302?
CVE-2026-45302 is a high-severity vulnerability in milamer parse-nested-form-data, published on 1 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-1321
Which versions are affected by CVE-2026-45302?
2 open source packages ship an affected version, including parse-nested-form-data.
| Package | Affected | Fixed in |
|---|---|---|
parse-nested-form-data npm | All versions | 1.0.1 |
parse-nested-form-data npm | All versions | 1.0.1 |
How do I fix CVE-2026-45302?
Upgrade parse-nested-form-data to 1.0.1 or later.
Is CVE-2026-45302 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45302 exists.
Sources
Also known as GHSA-xp7r-j8r6-j9h3.