---
id: CVE-2026-21712
title: >-
  A flaw in Node.js URL processing causes an assertion failure in native code
  when `url.format()` is called with a malformed internationalized domain name
  (IDN) containing invalid characters, crashing the Node.js process.
summary: >-
  A flaw in Node.js URL processing causes an assertion failure in native code
  when `url.format()` is called with a malformed internationalized domain name
  (IDN) containing invalid characters, crashing the Node.js process.
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cwe:
  - CWE-20
vendor: nodejs
product: node.js
affected:
  - 'node.js >= 24.0.0, <= 24.14.0'
  - 'node.js >= 25.0.0, <= 25.8.1'
published: '2026-03-30'
updated: '2026-08-19'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-21712'
references:
  - url: 'https://hackerone.com/reports/3546390'
    label: support@hackerone.com
  - url: 'https://nodejs.org/en/blog/vulnerability/march-2026-security-releases'
    label: support@hackerone.com
tags:
  - nvd
epss: 0.0032
epssPercentile: 0.22289
ingestedAt: '2026-08-19T14:40:19.027Z'
---

## Overview

A flaw in Node.js URL processing causes an assertion failure in native code when `url.format()` is called with a malformed internationalized domain name (IDN) containing invalid characters, crashing the Node.js process.

## Affected

- `node.js >= 24.0.0, <= 24.14.0`
- `node.js >= 25.0.0, <= 25.8.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.