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Fencer Intel
high 7.5

CVE-2026-91990 json

Tornado before 6.5.8 Memory Amplification DoS via multipart

published 3mo ago modified last mo. also EUVD-2026-78661 , GHSA-8423-8fgw-73vq

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

Tornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit. Attackers can send crafted multipart requests with many parts to create large transient lists, exhausting server memory and causing denial of service.

Patch / fix

  • pypi tornado 6.5.8
  • tornadoweb tornado 6.5.8
  • 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
  • python-tornado Ubuntu Pro 22.04 LTS 6.1.0-3ubuntu0.1~esm6

ubuntu advisories UBUNTU-CVE-2026-91990

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 6.5.8-0.el10_2.1
  • python3-tornado RHEL 10.2 6.5.8-0.el10_2.1
  • python-tornado RHEL 9 6.5.8-0.el9_8.1
  • python3-tornado RHEL 9 6.5.8-0.el9_8.1
  • python-tornado enterprise linux eus 10.0 6.5.8-0.el10_0.1
  • python3-tornado enterprise linux eus 10.0 6.5.8-0.el10_0.1

red hat advisories RHSA-2026:80741RHSA-2026:67147RHSA-2026:67146

  • python-tornado6 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.5-160000.7.1
  • python-tornado SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 4.5.3-150000.3.31.1
  • python-tornado6 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 6.3.2-150400.9.27.1

suse advisories SUSE-SU-2026:24121-1SUSE-SU-2026:24207-1SUSE-SU-2026:4404-1SUSE-SU-2026:4403-1

  • python-tornado6 openSUSE Leap 16.0 6.5-160000.7.1

opensuse advisories openSUSE-SU-2026:22059-1

  • python3-tornado AlmaLinux 9 6.5.8-0.el9_8.1
  • python3-tornado AlmaLinux 10 6.5.8-0.el10_2.1

almalinux advisories ALSA-2026:67146ALSA-2026:67147

Is CVE-2026-91990 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2026-91990 updated cvss 7.5

tornado: Tornado: Denial of Service via memory amplification in multipart parsing

  • Red Hat Exploit Intelligence exploit-intelligence-tech-preview/vulnerability-analysis-rhel9
    affected: workaround, no fix planned “Will not fix”
  • 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 Ansible Automation Platform 2 ansible-automation-platform-26/lightspeed-chatbot-rhel9
    affected: workaround, no fix available
  • 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 Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-9, python-tornado 6.1.0-3.el9ocp.1 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 2.7 ansible-automation-platform-27/lightspeed-chatbot-rhel9 1791250620
    fixed: vendor fix RHSA-2026:79378
  • Red Hat Enterprise Linux AppStream (v. 9) python-tornado 6.5.8-0.el9_8.1, python3-tornado 6.5.8-0.el9_8.1
    fixed: vendor fix RHSA-2026:67146
show 13 more
  • Red Hat Enterprise Linux AppStream (v. 10) python-tornado 6.5.8-0.el10_2.1, python3-tornado 6.5.8-0.el10_2.1
    fixed: vendor fix RHSA-2026:67147
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) python-tornado 6.5.10-0.el9_2.1, python3-tornado 6.5.10-0.el9_2.1
    fixed: vendor fix RHSA-2026:98106
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) python-tornado 6.5.10-0.el9_4.1, python3-tornado 6.5.10-0.el9_4.1
    fixed: vendor fix RHSA-2026:98107
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) python-tornado 6.5.8-0.el10_0.1, python3-tornado 6.5.8-0.el10_0.1
    fixed: vendor fix RHSA-2026:80741
  • 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, rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9 1791867208
    fixed: vendor fix RHSA-2026:87410
  • Red Hat OpenShift AI 3.4 rhoai/odh-feature-server-rhel9 1791863220, rhoai/odh-th06-cpu-torch210-py312-rhel9 1793084640, rhoai/odh-th06-rocm64-torch291-py312-rhel9 1792745990, rhoai/odh-th06-cuda130-torch210-py312-rhel9 1792748650, rhoai/odh-trustyai-nemo-guardrails-server-rhel9 1791556128, rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9 1792688615, +17 more
    fixed: vendor fix RHSA-2026:84734
  • Red Hat OpenShift AI 3.5 rhoai/odh-th-torch-cpu-py312-rhel9 1791926611, rhoai/odh-th-torch-cuda-py312-rhel9 1791927642, rhoai/odh-th-torch-rocm-py312-rhel9 1791925861, rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9 1791572004, rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9 1791816462, rhoai/odh-pipeline-runtime-pytorch-rocm-py312-rhel9 1791951049, +15 more
    fixed: vendor fix RHSA-2026:86891
  • Red Hat Migration Toolkit for Applications 8 mta/mta-solution-server-rhel9 Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/hub-rhel9 1791254555, ansible-automation-platform-27/gateway-rhel9 1791257377, ansible-automation-platform-27/hub-web-rhel9 1791264503, ansible-automation-platform-27/receptor-rhel9 1791251288, ansible-automation-platform-27/mcp-tools-rhel9 1790931895, ansible-automation-platform-27/controller-rhel9 1791253059, +26 more
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 8 pcs, pcs-snmp
    not affected: inline mitigations already exist
  • Red Hat Enterprise Linux 9 rhel9/keylime-verifier, rhel9/keylime-registrar Red Hat Enterprise Linux 10 rhel10/keylime-verifier, rhel10/keylime-registrar
    not affected: vulnerable code not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-th06-cpu-torch291-py312-rhel9, rhoai/odh-th06-cuda130-torch291-py312-rhel9
    not affected: component not present
  • 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, +64 more Red Hat OpenShift AI 3.4 rhoai/odh-cli-rhel9 1791509689, rhoai/odh-cli-rhel9 1792722177, rhoai/rhai-cli-rhel9 1791509689, rhoai/rhai-cli-rhel9 1792722177, rhoai/odh-automl-rhel9 1791535789, rhoai/odh-automl-rhel9 1792697253, +183 more Red Hat OpenShift AI 3.5 rhoai/odh-cli-rhel9 1791945905, rhoai/rhai-cli-rhel9 1791945905, rhoai/odh-automl-rhel9 1791916705, rhoai/odh-mlflow-rhel9 1791947857, rhoai/odh-autorag-rhel9 1791903266, rhoai/odh-trainer-rhel9 1791952138, +92 more Red Hat OpenShift Container Platform 4 python-flit 3.9.0-3.1.el9ocp, python-pep517 0.13.0-5.2.el9ocp
    not affected: vulnerable code 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
last mo.

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq 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

Affected packages

ecosystem package affected fixed in
pypi tornado
<6.5.8
6.5.8

Affected products

  • tornadoweb tornado

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Intel 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.

The maintainers of tornadoweb/tornado published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.