Security Digest · Vulnerability record
CVE-2025-63704: query-parser-string is vulnerable to Prototype Pollution
NPM package query-parser-string 1.0.0 is vulnerable to Prototype Pollution.
CVSS 9.8 Critical EPSS 0.5% · p40
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- 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.
From the GitHub advisory
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.
Weakness type: CWE-1321.
Product: query-string-parser (npm) · Assigned by: mitre · Published: 2026-05-07
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | query-string-parser | = 1.0.0 | none listed |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| n/a | n/a | see vendor advisory |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADP | 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- 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.
Timeline
- — CVE record published by mitre
- — GitHub-reviewed advisory GHSA-587p-w43q-4hjx published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-587p-w43q-4hjx github.com
- CVE.org record CVE-2025-63704 cve.org
- NVD entry CVE-2025-63704 nvd.nist.gov
Other references from the CVE record and advisory
- npmjs.com npmjs.com
- github.com github.com
- gist.github.com gist.github.com