# 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.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Jun 2026
- **Updated:** 2 Jun 2026
- **Also known as:** GHSA-xp7r-j8r6-j9h3

## 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 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-45302?

2 open source packages ship an affected version, including parse-nested-form-data.


| Package | Ecosystem | 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45302 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45302 exists.

Affected packages and fixed versions:
- parse-nested-form-data (npm): affected all versions; fixed in 1.0.1
- parse-nested-form-data (npm): affected all versions; fixed in 1.0.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-45302/ (Markdown: https://insights.sbomify.com/CVE-2026-45302/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45302
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45302
- OSV: https://osv.dev/vulnerability/CVE-2026-45302

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45302/
Summaries are generated and may contain mistakes; the official description above is the record.