---
id: CVE-2026-109924
title: undici is an HTTP client library for Node.js
summary: >-
  undici is an HTTP client library for Node.js. In versions 6.5.0 through
  6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, its EventSource client
  can be driven to exhaust process memory by a malicious or compromised
  Server-Sent Even…
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-770
vendor: undici
product: undici
affected:
  - undici >= 6.5.0 < 6.29.1
  - undici >= 7.0.0 < 7.30.1
  - undici >= 8.0.0 < 8.12.2
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T19:17:22.180'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109924'
references:
  - url: 'https://cna.openjsf.org/security-advisories.html'
    label: ce714d77-add3-4f53-aff5-83d477b104bb
  - url: 'https://github.com/nodejs/undici/security/advisories/GHSA-4qv8-2p9j-2685'
    label: ce714d77-add3-4f53-aff5-83d477b104bb
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-15T19:25:46.401Z'
---

## Overview

undici is an HTTP client library for Node.js. In versions 6.5.0 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, its EventSource client can be driven to exhaust process memory by a malicious or compromised Server-Sent Events peer. By sending millions of tiny completed data fields with no blank event separator, or a single unfinished line split across many chunks, the parser retains a growing amount of per-field and per-chunk state that the byte-based maxEventSize and maxResponseSize limits do not bound, and because maxResponseSize is enforced on the compressed body before decompression, a small compressed response can expand into enough retained memory to terminate the process. An application only needs to maintain an EventSource connection to an untrusted peer, which controls only the response, and availability is the only impact. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, which bound the retained parser state independently of the byte limits, and users should upgrade to one of those versions or later. There is no workaround.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.