CVE-2026-21717

Description

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**.. 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 Products

• ▸azl3 nodejs 20.14.0-15 on Azure Linux 3.0
• ▸cbl2 nodejs18 18.20.3-12 on CBL Mariner 2.0
• ▸azl3 nodejs 20.14.0-14 on Azure Linux 3.0
• ▸azl3 nodejs24 24.13.0-3 on Azure Linux 3.0

CVSS Vector