Description
Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated request body containing millions of separator-delimited fields can synchronously stall the single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to 104857600 bytes. This issue is fixed in version 6.5.8.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| tornadoweb | tornado | < 6.5.8 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | python-tornado | No fix yet | — |
| Debian 13 | python-tornado | No fix yet | — |
| Debian 12 | python-tornado | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | python-tornado | No fix yet | — |
| Ubuntu 26.04 LTS | python-tornado | No fix yet | — |
| Ubuntu 24.04 LTS | python-tornado | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | python-tornado | No fix yet | — |
| Ubuntu Pro 20.04 LTS | python-tornado | No fix yet | — |
| Ubuntu Pro 18.04 LTS | python-tornado | No fix yet | — |
| Ubuntu Pro 16.04 LTS | python-tornado | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | python-tornado +1 | 6.5.8-0.el10_2.1 | RHSA-2026:67147 |
| RHEL 9 | python-tornado +1 | 6.5.8-0.el9_8.1 | RHSA-2026:67146 |
| RHEL 8 | pcs +1 | 0.10.18-2.el8_10.10 | RHSA-2026:84798 |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8.8 TUS | pcs +1 | 0.10.15-4.el8_8.12 | RHSA-2026:84844 |
| RHEL 8.8 E4S | pcs +1 | 0.10.15-4.el8_8.12 | RHSA-2026:84844 |
| RHEL 8.6 EUS Long Life | pcs +1 | 0.10.12-6.el8_6.14 | RHSA-2026:85135 |
| RHEL 8.4 EUS Long Life | pcs +1 | 0.10.8-1.el8_4.12 | RHSA-2026:84843 |
| RHEL 8.4 AUS | pcs +1 | 0.10.8-1.el8_4.12 | RHSA-2026:84843 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | python3-tornado | 6.5.8-0.el10_2.1 | ALSA-2026:67147 |
| AlmaLinux 9 | python3-tornado | 6.5.8-0.el9_8.1 | ALSA-2026:67146 |
| AlmaLinux 8 | pcs +1 | 0.10.18-2.el8_10.10.alma.1 | ALSA-2026:84798 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | pcs | 0.10.18-2.el8_10.10 | RLSA-2026:84798 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLES 15 SP6 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLES 15 SP6 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
| SLES 15 SP5 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLES 15 SP5 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
| SLES 15 SP4 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLES 15 SP4 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
| SLES 3 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
Show 12 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | python-tornado6 | 6.5-160000.7.1 | SUSE-SU-2026:24207-1 |
| SLES for SAP 15 SP6 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLES for SAP 15 SP6 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
| SLES for SAP 15 SP5 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLES for SAP 15 SP5 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
| SLES for SAP 15 SP4 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLES for SAP 15 SP4 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
| SLES 16.0 | python-tornado6 | 6.5-160000.7.1 | SUSE-SU-2026:24207-1 |
| SLE Micro 6.2 | python-tornado6 | 6.5-160000.7.1 | SUSE-SU-2026:24121-1 |
| SLE Micro 6.1 | python-tornado6 | 6.4-slfo.1.1_7.1 | SUSE-SU-2026:23523-1 |
| SLE Micro 5.5 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLE Micro 5.4 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLE Micro 5.3 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLE HPC 15 SP5 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLE HPC 15 SP5 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
| SLE HPC 15 SP4 | python-tornado | 4.5.3-150000.3.28.1 | SUSE-SU-2026:4073-1 |
| SLE HPC 15 SP4 | python-tornado6 | 6.3.2-150400.9.24.1 | SUSE-SU-2026:4076-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | python-tornado6 | 6.5-160000.7.1 | openSUSE-SU-2026:22059-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | python3-tornado +1 | 6.1.0-2.amzn2023.0.10 | ALAS2023-2026-3093 |
| Amazon Linux 2023 | python3.13-tornado +1 | 6.4.2-1.amzn2023.0.5 | ALAS2023-2026-3092 |
| Amazon Linux 2 | python-tornado +1 | 4.2.1-3.amzn2.0.7 | ALAS2-2026-3925 |
| Amazon Linux 2 | python3-tornado +1 | 5.0.2-4.amzn2.0.10 | ALAS2-2026-3924 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | python-tornado | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | pcs +1 | 0.10.18-2.0.1.el8_10.10 | ELSA-2026-84798 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | dask-kubernetes | 2026.3.0-r12 | — |
| Wolfi rolling | kubeflow-pipelines-visualization-server | 2.17.1-r2 | — |
| Wolfi rolling | mitmproxy | 12.2.3-r8 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | tornado | < 6.5.8 | 6.5.8 | GHSA-mpf4-983q-p7j4 |
Advisories 22
- WID-SEC-2026-4029 Red Hat Enterprise Linux (python-tornado, resteasy-core, bubblewrap, pgvector): Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- ALSA-2026:67146 Important: python-tornado security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:67147 Important: python-tornado security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:84798 Important: pcs security update AlmaLinux Security Advisories · Oct 29, 2026
- SUSE-SU-2026:24207-1 Security update for python-tornado6 SUSE / openSUSE Security Updates · Oct 21, 2026
- RLSA-2026:84798 Important: pcs security update Rocky Linux Security Advisories · Oct 20, 2026
- RHSA-2026:85135 Red Hat Security Advisory: pcs security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:84843 Red Hat Security Advisory: pcs security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:84844 Red Hat Security Advisory: pcs security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:84798 Red Hat Security Advisory: pcs security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:67146 Red Hat Security Advisory: python-tornado security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:67147 Red Hat Security Advisory: python-tornado security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- ELSA-2026-84798 Important: pcs security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 20, 2026
- openSUSE-SU-2026:22059-1 Security update for python-tornado6 SUSE / openSUSE Security Updates · Oct 19, 2026
- SUSE-SU-2026:24121-1 Security update for python-tornado6 SUSE / openSUSE Security Updates · Oct 13, 2026
- ALAS2023-2026-3092 Important: python3.13-tornado security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- ALAS2023-2026-3093 Important: python-tornado security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- ALAS2-2026-3924 Important: python3-tornado security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- ALAS2-2026-3925 Important: python-tornado security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- SUSE-SU-2026:23523-1 Security update for python-tornado6 SUSE / openSUSE Security Updates · Sep 15, 2026
- SUSE-SU-2026:4076-1 Security update for python-tornado6 SUSE / openSUSE Security Updates · Sep 13, 2026
- SUSE-SU-2026:4073-1 Security update for python-tornado SUSE / openSUSE Security Updates · Sep 13, 2026