---
id: CVE-2026-18149
title: >-
  undici's retry handler can leave an already-exposed response body pending
  forever
summary: >-
  undici's retry handler can leave an already-exposed response body pending
  forever. When a server returns a successful response that declares a
  Content-Length, sends only part of the body, and closes the connection, the
  retry handler retr…
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-772
  - CWE-911
vendor: nodejs
product: undici
affected:
  - 'undici >= 7.11.0, < 7.29.1'
  - 'undici >= 8.0.0, < 8.10.2'
patched:
  - undici 8.10.2
published: '2026-09-04'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T20:41:26.947'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18149'
references:
  - url: 'https://cna.openjsf.org/security-advisories.html'
    label: ce714d77-add3-4f53-aff5-83d477b104bb
  - url: 'https://github.com/nodejs/undici/security/advisories/GHSA-pmjh-fq2x-6v4x'
    label: ce714d77-add3-4f53-aff5-83d477b104bb
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-18149.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-18149'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2528802'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-18149'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18149'
  - url: 'https://access.redhat.com/errata/RHSA-2026:66008'
  - url: 'https://access.redhat.com/errata/RHSA-2026:54438'
  - url: 'https://access.redhat.com/errata/RHSA-2026:54389'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
epss: 0.0036
epssPercentile: 0.29691
ingestedAt: '2026-09-08T19:08:49.593Z'
---

## Overview

undici's retry handler can leave an already-exposed response body pending forever. When a server returns a successful response that declares a Content-Length, sends only part of the body, and closes the connection, the retry handler retries the request. If the retry returns a non-retryable status such as 400, the handler forwards that new response downstream and replaces its internal response stream, but the original response body that the application still holds is never ended or destroyed. As a result calls that read that body never settle, and the configured body timeout does not fire because its timer is tied to the connection parser rather than the orphaned body. An attacker-controlled server can trigger this with two short responses without keeping a connection open, and repeated requests accumulate pending promises and streams that can exhaust application concurrency or memory. This affects undici versions from 7.11.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.

## Affected

- `undici >= 7.11.0, < 7.29.1`
- `undici >= 8.0.0, < 8.10.2`

## Remediation

Upgrade past the affected range:

- `undici 8.10.2`

## Vendor advisories

- **RHSA-2026:66008** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-09 · [advisory](https://access.redhat.com/errata/RHSA-2026:66008)
- **RHSA-2026:54438** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:54438)
- **RHSA-2026:54389** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:54389)
- **Red Hat VEX** · Moderate · affected: OpenShift Pipelines, Red Hat Build of Podman Desktop, Red Hat Developer Hub, Red Hat Enterprise Linux 10, Red Hat Hardened Images, Red Hat OpenShift AI (RHOAI), … · no fix planned: Red Hat Hardened Images, OpenShift Pipelines, Red Hat Build of Podman Desktop, Red Hat Developer Hub, … · updated 2026-09-09 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-18149.json)