---
id: GHSA-fg72-q65g-wm5w
title: >-
  Duplicate Advisory: H3: Unbounded Chunked Cookie Count in Session Cleanup Loop
  may Lead to Denial of Service
summary: >-
  Duplicate Advisory: H3: Unbounded Chunked Cookie Count in Session Cleanup Loop
  may Lead to Denial of Service
severity: high
cvss: 7.5
cwe:
  - CWE-400
vendor: h3
product: h3
ecosystem: npm
affected:
  - 'h3 >= 2.0.0-beta.4, < 2.0.1-rc.18'
published: '2026-09-06'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T23:46:36Z'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-fg72-q65g-wm5w'
references:
  - url: 'https://github.com/h3js/h3/security/advisories/GHSA-q5pr-72pq-83v3'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86250'
  - url: >-
      https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-denial-of-service-via-unbounded-chunked-cookie
  - url: 'https://github.com/advisories/GHSA-fg72-q65g-wm5w'
tags:
  - ghsa
  - npm
ingestedAt: '2026-10-01T00:33:27.743Z'
---

## Overview

## Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-q5pr-72pq-83v3. This link is maintained to preserve external references.

## Original Description
h3 versions before 2.0.1-rc.18 fail to validate the chunk count parsed from user-controlled cookie values in setChunkedCookie() and deleteChunkedCookie() functions. Attackers can send a crafted cookie header with an extremely large chunk count to trigger an O(n²) cleanup loop that hangs the server process.

## Affected packages

- `h3 >= 2.0.0-beta.4, < 2.0.1-rc.18`

## Remediation

Refer to the advisory for the patched release.