---
id: CVE-2026-103262
title: >-
  Tornado versions before 6.5.9 contain an unbounded memory accumulation
  vulnerability in CurlAsyncHTTPClient that allows remote attackers to cause
  denial of service by sending a compressed response
summary: >-
  Tornado versions before 6.5.9 contain an unbounded memory accumulation
  vulnerability in CurlAsyncHTTPClient that allows remote attackers to cause
  denial of service by sending a compressed response. Attackers can send a
  gzip-encoded decom…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-409
vendor: tornadoweb
product: tornado
affected:
  - tornado < 6.5.9
published: '2026-10-01'
updated: '2026-10-01'
sourceUpdated: '2026-10-01T11:17:21.177'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-103262'
references:
  - url: >-
      https://github.com/tornadoweb/tornado/commit/e412435febba4569c552c5c9054f1bf92bd171a9
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/tornadoweb/tornado/security/advisories/GHSA-chx6-46f5-w4vp
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/tornado-before-6.5.9-denial-of-service-via-curlasynchttpclient
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-01T11:42:53.805Z'
---

## Overview

Tornado versions before 6.5.9 contain an unbounded memory accumulation vulnerability in CurlAsyncHTTPClient that allows remote attackers to cause denial of service by sending a compressed response. Attackers can send a gzip-encoded decompression bomb that accumulates in memory without size limits, causing the application process to be killed by out-of-memory conditions.

## Remediation

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