CVE-2025-23167: Node.js Node

Medium severity, CVSS 6.5. EPSS: 0.5% chance of exploitation in the next 30 days.

A flaw in Node.js 20's HTTP parser allows improper termination of HTTP/1 headers using `\r\n\rX` instead of the required `\r\n\r\n`. This inconsistency enables request smuggling, allowing attackers to bypass proxy-based access controls and submit unauthorized requests. The issue was resolved by upgrading `llhttp` to version 9, which enforces correct header termination. Impact: * This vulnerability affects only Node.js 20.x users prior to the `llhttp` v9 upgrade.

Affected products

• Node.js Node: from 4.0, before 5 (fixed in 5); from 5.0, before 6 (fixed in 6); from 6.0, before 7 (fixed in 7); from 7.0, before 8 (fixed in 8); from 8.0, before 9 (fixed in 9); from 9.0, before 10 (fixed in 10); …

Published 2025-05-19. Last modified 2026-06-17.