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Fencer Vulns
high 7.5

CVE-2026-103262 json

Tornado before 6.5.9 Denial of Service via CurlAsyncHTTPClient

published 2026-09-30 39 d ago modified 2026-10-06 34 d ago also GHSA-chx6-46f5-w4vp , EUVD-2026-90656

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

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 decompression bomb that accumulates in memory without size limits, causing the application process to be killed by out-of-memory conditions.

Patch / fix

  • pypi tornado 6.5.9
  • tornadoweb tornado 6.5.9
  • python-tornado Ubuntu 24.04 LTS 6.4.0-1ubuntu0.6
  • python-tornado Ubuntu 26.04 LTS 6.5.4-0.1ubuntu0.2
  • python-tornado Ubuntu Pro 16.04 LTS 4.2.1-1ubuntu3.1+esm4
  • python-tornado Ubuntu Pro 18.04 LTS 4.5.3-1ubuntu0.2+esm4

ubuntu advisories UBUNTU-CVE-2026-103262

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python-tornado RHEL 10.2 6.5.10-1.el10_2.1
  • python3-tornado RHEL 10.2 6.5.10-1.el10_2.1
  • python-tornado RHEL 9 6.5.10-1.el9_8.1
  • python3-tornado RHEL 9 6.5.10-1.el9_8.1

red hat advisories RHSA-2026:82041RHSA-2026:82040

  • python3-tornado AlmaLinux 9 6.5.10-1.el9_8.1
  • python3-tornado AlmaLinux 10 6.5.10-1.el10_2.1

almalinux advisories ALSA-2026:82040ALSA-2026:82041

  • python-tornado Rocky Linux 10 6.5.10-1.el10_2.1
  • python-tornado Rocky Linux 9 6.5.10-1.el9_8.1

rocky linux advisories RLSA-2026:82041RLSA-2026:82040

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-103262 updated cvss 7.5

tornado: Tornado: Denial of Service via decompression bomb in CurlAsyncHTTPClient

  • Red Hat Lightspeed Core lightspeed-core/rag-tool-cpu-rhel9, lightspeed-core/lightspeed-stack-rhel9, lightspeed-core/rag-tool-cuda-12.9-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/disk-image-cuda-rhel9
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-llama-stack-core-rhel9, rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9, rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9, rhoai/odh-pipeline-runtime-pytorch-rocm-py312-rhel9, rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9, rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9, +13 more Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9 Red Hat OpenStack Platform 16.2 rhosp-rhel8/openstack-redis, rhosp-rhel8/openstack-haproxy, rhosp-rhel8/openstack-mariadb, rhosp-rhel8/openstack-rabbitmq, rhosp-rhel8/openstack-ovn-northd, rhosp-rhel8/openstack-manila-share, +2 more Red Hat OpenStack Platform 17.1 rhosp-rhel9/openstack-redis, rhosp-rhel9/openstack-haproxy, rhosp-rhel9/openstack-mariadb, rhosp-rhel9/openstack-rabbitmq, rhosp-rhel9/openstack-ovn-northd, rhosp-rhel9/openstack-manila-share, +2 more
    affected: workaround, no fix available
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/lightspeed-chatbot-rhel9 1791978798
    fixed: vendor fix RHSA-2026:87120
  • Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/lightspeed-chatbot-rhel9 1792385971
    fixed: vendor fix RHSA-2026:87124
  • Red Hat Enterprise Linux AppStream (v. 9) python-tornado 6.5.10-1.el9_8.1, python3-tornado 6.5.10-1.el9_8.1
    fixed: vendor fix RHSA-2026:82040
  • Red Hat Enterprise Linux AppStream (v. 10) python-tornado 6.5.10-1.el10_2.1, python3-tornado 6.5.10-1.el10_2.1
    fixed: vendor fix RHSA-2026:82041
show 10 more
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) python-tornado 6.5.10-0.el10_0.1, python3-tornado 6.5.10-0.el10_0.1
    fixed: vendor fix RHSA-2026:91583
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) python-tornado 6.4.2-2.el9_6.7, python3-tornado 6.4.2-2.el9_6.7
    fixed: vendor fix RHSA-2026:90283
  • Red Hat OpenShift AI 2.25 rhoai/odh-feature-server-rhel9 1792148523
    fixed: vendor fix RHSA-2026:87410
  • Red Hat OpenShift AI 3.4 rhoai/odh-feature-server-rhel9 1791863220, rhoai/odh-trustyai-nemo-guardrails-server-rhel9 1791556128
    fixed: vendor fix RHSA-2026:84734
  • Red Hat OpenShift Container Platform 4.22 rhcos 4.22.9.8.202610241758
    fixed: vendor fix RHSA-2026:89197
  • Red Hat Migration Toolkit for Applications 8 mta/mta-solution-server-rhel9 Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/hub-rhel9 1791947385, ansible-automation-platform-26/gateway-rhel9 1791971533, ansible-automation-platform-26/hub-web-rhel9 1791952205, ansible-automation-platform-26/receptor-rhel9 1791968536, ansible-automation-platform-26/mcp-tools-rhel9 1791941340, ansible-automation-platform-26/controller-rhel9 1791947602, +24 more Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/hub-rhel9 1792388670, ansible-automation-platform-27/gateway-rhel9 1792429216, ansible-automation-platform-27/hub-web-rhel9 1792394496, ansible-automation-platform-27/receptor-rhel9 1792139928, ansible-automation-platform-27/mcp-tools-rhel9 1792425046, ansible-automation-platform-27/controller-rhel9 1792389457, +26 more
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 8 pcs, pcs-snmp
    not affected: vulnerable code cannot be controlled by adversary
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-th-torch-cpu-py312-rhel9, rhoai/odh-th-torch-cuda-py312-rhel9, rhoai/odh-th-torch-rocm-py312-rhel9, rhoai/odh-th06-cpu-torch210-py312-rhel9, rhoai/odh-th06-cpu-torch291-py312-rhel9, rhoai/odh-th06-rocm64-torch291-py312-rhel9, +2 more
    not affected: vulnerable code not in execute path
  • Red Hat OpenShift AI 2.25 rhoai/odh-rhel9-operator 1792570619, rhoai/odh-vllm-cpu-rhel9 1792018436, rhoai/odh-dashboard-rhel9 1791853525, rhoai/odh-modelmesh-rhel9 1790881700, rhoai/odh-operator-bundle 1792571069, rhoai/odh-vllm-cuda-rhel9 1791358976, +65 more Red Hat OpenShift AI 3.4 rhoai/odh-cli-rhel9 1791509689, rhoai/rhai-cli-rhel9 1791509689, rhoai/odh-automl-rhel9 1791535789, rhoai/odh-mlflow-rhel9 1791865967, rhoai/odh-autorag-rhel9 1791557539, rhoai/odh-trainer-rhel9 1791869783, +98 more
    not affected: vulnerable code not present
  • Red Hat OpenShift Container Platform 4 python-flit 3.9.0-3.1.el9ocp, python-pep517 0.13.0-5.2.el9ocp, python-tornado 6.1.0-3.el9ocp.1
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
34 d ago

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/tornadoweb/tornado/security/advisories/GHSA-chx6-46f5-w4vp referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi tornado
<6.5.9
6.5.9

Affected products

  • tornadoweb tornado

Classification

Weakness
  • CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.