---
id: CVE-2026-21717
title: >-
  A flaw in V8's string hashing mechanism causes integer-like strings to be
  hashed to their numeric value, making hash collisions trivially predictable
summary: >-
  A flaw in V8's string hashing mechanism causes integer-like strings to be
  hashed to their numeric value, making hash collisions trivially predictable.
  By crafting a request that causes many such collisions in V8's internal string
  table, …
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-328
vendor: nodejs
product: node.js
affected:
  - node.js <= 20.20.1
  - 'node.js >= 22.0.0, <= 22.22.1'
  - '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-2026-21717'
references:
  - url: 'https://nodejs.org/en/blog/vulnerability/march-2026-security-releases'
    label: support@hackerone.com
tags:
  - nvd
  - exploit-available
epss: 0.00268
epssPercentile: 0.16802
ingestedAt: '2026-08-19T13:39:32.947Z'
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/open-flaw/CVE-2026-21717'
  checkedAt: '2026-09-25T08:20:52.894Z'
exploitAvailable: true
---

## Overview

A flaw in V8's string hashing mechanism causes integer-like strings to be hashed to their numeric value, making hash collisions trivially predictable. By crafting a request that causes many such collisions in V8's internal string table, an attacker can significantly degrade performance of the Node.js process.

The most common trigger is any endpoint that calls `JSON.parse()` on attacker-controlled input, as JSON parsing automatically internalizes short strings into the affected hash table.

This vulnerability affects **20.x, 22.x, 24.x, and 25.x**.

## Affected

- `node.js <= 20.20.1`
- `node.js >= 22.0.0, <= 22.22.1`
- `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.