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Fencer Vulns
high 7.5

CVE-2026-31958 json

Tornado has a DoS due to too many multipart parts

published 2026-03-11 7 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-11323 , GHSA-qjxf-f2mg-c6mc , PYSEC-2026-140

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits
0
none known

Summary

Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.

Patch / fix

  • pypi tornado 6.5.5
  • tornadoweb tornado 6.5.5
  • python-tornado Debian 14 6.5.5-1

debian advisories DEBIAN-CVE-2026-31958

  • python-tornado Ubuntu 24.04 LTS 6.4.0-1ubuntu0.5
  • python-tornado Ubuntu 25.10 6.4.2-3ubuntu0.3
  • python-tornado Ubuntu 26.04 LTS 6.5.4-0.1ubuntu0.1
  • python-tornado Ubuntu Pro 16.04 LTS 4.2.1-1ubuntu3.1+esm3
  • python-tornado Ubuntu Pro 18.04 LTS 4.5.3-1ubuntu0.2+esm3
  • python-tornado Ubuntu Pro 22.04 LTS 6.1.0-3ubuntu0.1~esm5

ubuntu advisories UBUNTU-CVE-2026-31958

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 9 6.5.5-1.el9_8
  • python3-tornado RHEL 9 6.5.5-1.el9_8
  • python-tornado RHEL 10.2 6.5.5-1.el10_2
  • python3-tornado RHEL 10.2 6.5.5-1.el10_2
  • python-tornado RHEL 9 6.5.5-1.el9_7.1
  • python3-tornado RHEL 9 6.5.5-1.el9_7.1
  • python-tornado RHEL 10.1 6.5.5-1.el10_1.1
  • python3-tornado RHEL 10.1 6.5.5-1.el10_1.1

red hat advisories RHSA-2026:24342RHSA-2026:20810RHSA-2026:20577RHSA-2026:20573RHSA-2026:20572RHSA-2026:19189

  • venv-salt-minion Manager Client Tools for RHEL, Liberty and Clones 9-CLIENT-TOOLS 3006.0-1.76.1
  • venv-salt-minion Multi Linux Manager Tools SLE-Micro-5, Multi Linux Manager Tools SLE-15 3006.0-150002.5.12.2
  • venv-salt-minion Multi Linux Manager Tools SLE-12 3006.0-120002.5.12.1
  • spacecmd RES-7:Update:Products:MultiLinuxManagerTools:Update, Multi Linux Manager Tools RES-7 5.1.13-70002.3.9.1
  • saltbundlepy RES-7:Update:Products:MultiLinuxManagerTools:Update 3.11.13-70002.4.9.1
  • venv-salt-minion RES-7:Update:Products:MultiLinuxManagerTools:Update, Multi Linux Manager Tools RES-7 3006.0-70002.5.12.1
  • saltbundlepy-core RES-7:Update:Products:MultiLinuxManagerTools:Update 3.11.13-70002.4.9.1
  • saltbundlepy-pyzmq RES-7:Update:Products:MultiLinuxManagerTools:Update 25.1.2-70002.3.9.2

suse advisories SUSE-EL-9-CLIENT-TOOLS-2026-2255SUSE-SU-2026:1525-1SUSE-SU-2026:1523-1SUSE-SU-2026:1521-1SUSE-SU-2026:1520-1SUSE-SU-2026:1519-1

  • salt openSUSE Leap 16.0 3006.0-160000.5.1
  • salt-test openSUSE Leap 16.0 3006.0-160000.5.1
  • python-tornado6 openSUSE Leap 16.0 6.5-160000.4.1
  • salt openSUSE Tumbleweed 3006.0-56.1
  • python-tornado6 openSUSE Tumbleweed 6.5.5-1.1

opensuse advisories openSUSE-SU-2026:20918-1openSUSE-SU-2026:20406-1openSUSE-SU-2026:10389-1openSUSE-SU-2026:10374-1

  • python3-tornado AlmaLinux 10 6.5.5-1.el10_2
  • python3-tornado AlmaLinux 9 6.5.5-1.el9_8
  • python3-tornado AlmaLinux 10 6.5.5-1.el10_1.1
  • python3-tornado AlmaLinux 9 6.5.5-1.el9_7.1
  • pcs AlmaLinux 8 0.10.18-2.el8_10.9.alma.1
  • pcs-snmp AlmaLinux 8 0.10.18-2.el8_10.9.alma.1

almalinux advisories ALSA-2026:19034ALSA-2026:19189ALSA-2026:13641ALSA-2026:13670ALSA-2026:8093

  • python-tornado Rocky Linux 10 6.5.5-1.el10_1.1
  • python-tornado Rocky Linux 9 6.5.5-1.el9_7.1
  • pcs Rocky Linux 8 0.10.18-2.el8_10.9

rocky linux advisories RLSA-2026:19034RLSA-2026:19189RLSA-2026:13641RLSA-2026:13670RLSA-2026:8093

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-2026-31958 updated cvss 5.3

tornado-python: Tornado: Denial of Service via large multipart bodies

  • Red Hat Lightspeed Core lightspeed-core/rag-tool-rhel9, lightspeed-core/lightspeed-stack-rhel9 Red Hat Enterprise Linux 9 pcs, pcs-snmp Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/disk-image-cuda-rhel9
    affected: workaround, no fix available
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-trustyai-ragas-lls-provider-dsp-rhel9
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 9) python-tornado 6.5.5-1.el9_8, python3-tornado 6.5.5-1.el9_8, python-tornado 6.5.5-1.el9_7.1, python3-tornado 6.5.5-1.el9_7.1
    fixed: vendor fix RHSA-2026:13670
  • Red Hat Enterprise Linux AppStream (v. 10) python-tornado 6.5.5-1.el10_2, python3-tornado 6.5.5-1.el10_2, python-tornado 6.5.5-1.el10_1.1, python3-tornado 6.5.5-1.el10_1.1
    fixed: vendor fix RHSA-2026:13641
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) python-tornado 6.4.2-1.el9_2.2, python3-tornado 6.4.2-1.el9_2.2
    fixed: vendor fix RHSA-2026:20573
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) python-tornado 6.4.2-1.el10_0.2, python3-tornado 6.4.2-1.el10_0.2
    fixed: vendor fix RHSA-2026:20577
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) python-tornado 6.4.2-1.el9_4.2, python3-tornado 6.4.2-1.el9_4.2
    fixed: vendor fix RHSA-2026:20810
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) python-tornado 6.4.2-2.el9_6.3, python3-tornado 6.4.2-2.el9_6.3
    fixed: vendor fix RHSA-2026:20572
show 15 more
  • Red Hat Enterprise Linux High Availability AUS (v.8.4) pcs 0.10.8-1.el8_4.11, pcs-snmp 0.10.8-1.el8_4.11
    fixed: vendor fix RHSA-2026:11493
  • Red Hat Enterprise Linux High Availability E4S (v.8.6) pcs 0.10.12-6.el8_6.13, pcs-snmp 0.10.12-6.el8_6.13
    fixed: vendor fix RHSA-2026:11494
  • Red Hat Enterprise Linux High Availability E4S (v.8.8) pcs 0.10.15-4.el8_8.11, pcs-snmp 0.10.15-4.el8_8.11
    fixed: vendor fix RHSA-2026:11495
  • Red Hat Enterprise Linux High Availability E4S (v.9.0) pcs 0.11.1-10.el9_0.11, pcs-snmp 0.11.1-10.el9_0.11
    fixed: vendor fix RHSA-2026:11454
  • Red Hat Enterprise Linux High Availability TUS (v.8.6) pcs 0.10.12-6.el8_6.13, pcs-snmp 0.10.12-6.el8_6.13
    fixed: vendor fix RHSA-2026:11494
  • Red Hat Enterprise Linux High Availability TUS (v.8.8) pcs 0.10.15-4.el8_8.11, pcs-snmp 0.10.15-4.el8_8.11
    fixed: vendor fix RHSA-2026:11495
  • Red Hat Enterprise Linux HighAvailability (v. 8) pcs 0.10.18-2.el8_10.9, pcs-snmp 0.10.18-2.el8_10.9
    fixed: vendor fix RHSA-2026:8093
  • Red Hat Enterprise Linux HighAvailability EUS EXTENSION (v.8.4) pcs 0.10.8-1.el8_4.11, pcs-snmp 0.10.8-1.el8_4.11
    fixed: vendor fix RHSA-2026:11493
  • Red Hat Enterprise Linux ResilientStorage (v. 8) pcs 0.10.18-2.el8_10.9, pcs-snmp 0.10.18-2.el8_10.9
    fixed: vendor fix RHSA-2026:8093
  • Red Hat Enterprise Linux ResilientStorage E4S (v.9.0) pcs 0.11.1-10.el9_0.11, pcs-snmp 0.11.1-10.el9_0.11
    fixed: vendor fix RHSA-2026:11454
  • Red Hat Enterprise Linux Server Optional (v. 7 ELS) python-tornado 4.2.1-5.el7_9.3
    fixed: vendor fix RHSA-2026:24342
  • Red Hat OpenShift AI 2.25 rhoai 1775144403, rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9 1780069491, rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9 1780078429, rhoai/odh-pipeline-runtime-pytorch-rocm-py312-rhel9 1780078632, rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9 1780069205, rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9 1780069224, +13 more
    fixed: vendor fix RHSA-2026:10184
  • Red Hat OpenShift AI 3.3 rhoai/odh-llama-stack-core-rhel9 1782471587, rhoai/odh-trustyai-nemo-guardrails-server-rhel9 1782471606, rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9 1782471678, rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9 1790331344, rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9 1782471731, rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9 1789651383, +20 more
    fixed: vendor fix RHSA-2026:37275
  • Red Hat External Secrets Operator for Red Hat OpenShift external-secrets-operator/external-secrets-rhel9, external-secrets-operator/bitwarden-sdk-server-rhel9, external-secrets-operator/external-secrets-operator-rhel9, external-secrets-operator/external-secrets-operator-bundle
    not affected: vulnerable code not in execute path
  • Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9 Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9 Red Hat OpenShift AI 2.25 rhoai 1776243157, rhoai 1776243163, rhoai 1776243192, rhoai 1776243217, rhoai 1776243229, rhoai 1776243238, +129 more Red Hat OpenShift AI 3.3 rhoai/odh-cli-rhel9 1782471642, rhoai/odh-cli-rhel9 1790070206, rhoai/rhai-cli-rhel9 1782471642, rhoai/rhai-cli-rhel9 1790070206, rhoai/odh-mlflow-rhel9 1782917849, rhoai/odh-mlflow-rhel9 1789653606, +134 more Red Hat OpenShift Container Platform 4 python-pep517, python-tornado, openshift/ose-rhel-coreos-9
    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
none
Automatable
yes
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

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
GitHub 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
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 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
<6.5.5
6.5.5

Affected products

  • tornadoweb tornado

Classification

Weakness
  • 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.

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