---
title: "CVE-2025-63704: query-parser-string is vulnerable to Prototype Pollution"
url: https://erroneo.us/security/cve/CVE-2025-63704/
description: "CVE-2025-63704 (query-string-parser (npm)): NPM package query-parser-string 1.0.0 is vulnerable to Prototype Pollution. The package does not properly…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-07
date_modified: 2026-05-12
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-63704"
kev: false
cvss: 9.8
epss: 0.00476
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-63704: query-parser-string is vulnerable to Prototype Pollution

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.5% , percentile 40: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 40% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes query-string-parser (npm) = 1.0.0, no fixed version listed . Check your lockfile, including transitive dependencies.

## What it is

NPM package query-parser-string 1.0.0 is vulnerable to Prototype Pollution. The package does not properly sanitize user supplied query parameters and merges them to the newly created object.

## Affected packages

- npm `query-string-parser` = 1.0.0 → fixed: none listed

## Affected products (CVE record)

- n/a n/a: see advisory

## Severity

- CISA-ADP CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.48% probability of exploitation activity in the next 30 days; percentile 40.

## Sources

- [GitHub Advisory GHSA-587p-w43q-4hjx](https://github.com/advisories/GHSA-587p-w43q-4hjx)
- [CVE.org record CVE-2025-63704](https://www.cve.org/CVERecord?id=CVE-2025-63704)
- [NVD entry CVE-2025-63704](https://nvd.nist.gov/vuln/detail/CVE-2025-63704)
- [npmjs.com](https://www.npmjs.com/package/query-string-parser?activeTab=readme)
- [github.com](https://github.com/victorteokw/query-string-parser/issues/3)
- [gist.github.com](https://gist.github.com/6en6ar/d62f614dbb2b1032b5e45a56fe26ec8b)

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Source page: https://erroneo.us/security/cve/CVE-2025-63704/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt