---
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
patched:
  - tornado 6.5.9
published: '2026-10-01'
updated: '2026-10-06'
sourceUpdated: '2026-10-06T01:16:32.767'
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
  - url: >-
      https://github.com/tornadoweb/tornado/security/advisories/GHSA-chx6-46f5-w4vp
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://github.com/tornadoweb/tornado/pull/3719'
  - url: >-
      https://github.com/tornadoweb/tornado/commit/15f056080d8e456f92cca8ad0c33e5a5480414ac
  - url: >-
      https://github.com/tornadoweb/tornado/commit/6564e0a0922c16f239d3a18adccd04736e380c89
  - url: >-
      https://github.com/tornadoweb/tornado/commit/aa2eb0d989716ac00fe8d7a9919b81c1eccd6ec4
  - url: 'https://github.com/tornadoweb/tornado'
  - url: 'https://github.com/tornadoweb/tornado/releases/tag/v6.5.9'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-103262.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-103262'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2544534'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-103262'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-103262'
  - url: 'https://access.redhat.com/errata/RHSA-2026:82041'
  - url: 'https://access.redhat.com/errata/RHSA-2026:82040'
  - url: 'https://access.redhat.com/errata/RHSA-2026:84734'
tags:
  - nvd
  - cve.org
  - exploit-available
  - osv
  - pip
  - csaf
  - vex
  - red-hat
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-06T00:08:34.189311Z'
epss: 0.00628
epssPercentile: 0.49884
aliases:
  - GHSA-chx6-46f5-w4vp
ecosystem: pip
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.

## Package advisory (CVE-2026-103262)

Affected packages:

- `tornado < 6.5.9`

Patched in:

- `tornado 6.5.9`

Source: https://osv.dev/vulnerability/GHSA-chx6-46f5-w4vp

## Vendor advisories

- **Red Hat VEX** · Important · affected: Lightspeed Core, OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI), Red Hat OpenShift Container Platform 4, … · no fix planned: OpenShift Lightspeed, Red Hat Enterprise Linux AI (RHEL AI) 3, Lightspeed Core, Red Hat Ansible Automation Platform 2, … · updated 2026-10-19 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-103262.json)
- **RHSA-2026:82041** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:82041)
- **RHSA-2026:82040** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-10-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:82040)
- **RHSA-2026:84734** · Red Hat · fixed in: Red Hat OpenShift AI 3.4 · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:84734)