---
id: CVE-2026-6733
title: undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse
summary: undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse
severity: low
cvss: 3.7
cwe:
  - CWE-367
vendor: undici
product: undici
affected:
  - undici < 6.27.0
  - 'undici >= 7.0.0, < 7.28.0'
  - 'undici >= 8.0.0, < 8.5.0'
patched:
  - undici 6.27.0
  - undici 7.28.0
  - undici 8.5.0
published: '2026-06-19'
updated: '2026-06-19'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-35p6-xmwp-9g52'
references:
  - url: 'https://github.com/nodejs/undici/security/advisories/GHSA-35p6-xmwp-9g52'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-6733'
  - url: 'https://hackerone.com/reports/3582376'
  - url: 'https://cna.openjsf.org/security-advisories.html'
  - url: 'https://github.com/advisories/GHSA-35p6-xmwp-9g52'
tags:
  - ghsa
  - npm
epss: 0.0027
epssPercentile: 0.17093
ingestedAt: '2026-06-22T15:59:08.198Z'
ecosystem: npm
---

## Overview

## Impact

Undici's HTTP/1.1 client is vulnerable to response queue poisoning on reused keep-alive sockets. An attacker-controlled upstream server can inject an unsolicited HTTP/1.1 response onto an idle socket after a request completes. When the client dispatches the next request on that socket, it associates the injected response with the new request, causing responses to be delivered to the wrong requests.

This requires an attacker-controlled or compromised upstream HTTP/1.1 server and keep-alive connection reuse.

## Patches

Upgrade to undici v6.27.0, v7.28.0 or v8.5.0.

## Workarounds

Disable keep-alive connection reuse by setting `keepAliveTimeout: 0` on the Client or Pool.

## Affected packages

- `undici < 6.27.0`
- `undici >= 7.0.0, < 7.28.0`
- `undici >= 8.0.0, < 8.5.0`

## Remediation

Upgrade to a patched release:

- `undici 6.27.0`
- `undici 7.28.0`
- `undici 8.5.0`