Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| tornadoweb | tornado | < 6.5.8 | 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 | 6.5.5-5ubuntu1.1 | USN-8952-1 |
| Ubuntu 26.04 LTS | python-tornado | 6.5.4-0.1ubuntu0.2 | USN-8952-1 |
| Ubuntu 24.04 LTS | python-tornado | 6.4.0-1ubuntu0.6 | USN-8952-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | python-tornado | 6.1.0-3ubuntu0.1~esm6 | USN-8952-1 |
| Ubuntu Pro 20.04 LTS | python-tornado | 6.0.3+really5.1.1-3ubuntu0.1~esm7 | USN-8952-1 |
| Ubuntu Pro 18.04 LTS | python-tornado | 4.5.3-1ubuntu0.2+esm4 | USN-8952-1 |
| Ubuntu Pro 16.04 LTS | python-tornado | 4.2.1-1ubuntu3.1+esm4 | USN-8952-1 |
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 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10.0 EUS | python-tornado +1 | 6.5.8-0.el10_0.1 | RHSA-2026:80741 |
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 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLES 15 SP6 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLES 15 SP6 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
| SLES 15 SP5 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLES 15 SP5 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
| SLES 15 SP4 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLES 15 SP4 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
| SLES 3 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
Show 11 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 | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLES for SAP 15 SP6 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
| SLES for SAP 15 SP5 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLES for SAP 15 SP5 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
| SLES for SAP 15 SP4 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLES for SAP 15 SP4 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
| 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 5.5 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLE Micro 5.4 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLE Micro 5.3 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLE HPC 15 SP5 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLE HPC 15 SP5 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
| SLE HPC 15 SP4 | python-tornado | 4.5.3-150000.3.31.1 | SUSE-SU-2026:4404-1 |
| SLE HPC 15 SP4 | python-tornado6 | 6.3.2-150400.9.27.1 | SUSE-SU-2026:4403-1 |
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.amzn2023.0.11 | ALAS2023-2026-3177 |
| Amazon Linux 2023 | python3.13-tornado +1 | 6.4.2-1.amzn2023.0.6 | ALAS2023-2026-3176 |
| Amazon Linux 2 | python-tornado +1 | 4.2.1-3.amzn2.0.8 | ALAS2-2026-3976 |
| Amazon Linux 2 | python3-tornado +1 | 5.0.2-4.amzn2.0.11 | ALAS2-2026-3975 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | python-tornado | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | tornado | < 6.5.8 | 6.5.8 | GHSA-8423-8fgw-73vq |
Advisories 16
- WID-SEC-2026-3870 Red Hat Enterprise Linux (python-tornado): Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 10, 2026
- USN-8952-1 python-tornado vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 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
- SUSE-SU-2026:24207-1 Security update for python-tornado6 SUSE / openSUSE Security Updates · Oct 21, 2026
- RHSA-2026:80741 Red Hat Security Advisory: python-tornado 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
- 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
- ALAS2-2026-3976 Important: python-tornado security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- ALAS2-2026-3975 Important: python3-tornado security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- ALAS2023-2026-3176 Important: python3.13-tornado security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- ALAS2023-2026-3177 Important: python-tornado security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- SUSE-SU-2026:4403-1 Security update for python-tornado6 SUSE / openSUSE Security Updates · Oct 1, 2026
- SUSE-SU-2026:4404-1 Security update for python-tornado SUSE / openSUSE Security Updates · Oct 1, 2026
References
- GitHub Security Advisory (GHSA-8423-8fgw-73vq) vendor-advisory
- VulnCheck Advisory: Tornado before 6.5.8 Memory Amplification DoS via multipart third-party-advisory