Description
Tornado before 6.4.1 ignores duplicate Transfer-Encoding: chunked headers, treating requests as having no message body and parsing the chunked body as a subsequent request. Attackers can exploit this inconsistency when Tornado is deployed behind proxies to perform HTTP request smuggling, enabling access control bypass, cache poisoning, or connection desynchronization.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| tornadoweb | tornado | < 6.4.1 | 6.4.1 |
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 | 6.4.1-1 | — |
| Debian 13 | python-tornado | 6.4.1-1 | — |
| 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 9 | pcs +1 | 0.11.8-1.el9_5.2 | RHSA-2025:2471 |
| RHEL 9 | python-tornado +1 | 6.4.2-1.el9_5 | RHSA-2024:10590 |
| RHEL 8 | pcs +1 | 0.10.18-2.el8_10.10 | RHSA-2026:84798 |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9.4 EUS | pcs +1 | 0.11.7-2.el9_4.3 | RHSA-2025:2470 |
| RHEL 9.4 EUS | python-tornado +1 | 6.4.2-1.el9_4 | RHSA-2024:10843 |
| RHEL 9.2 EUS | pcs +1 | 0.11.4-7.el9_2.4 | RHSA-2025:3108 |
| RHEL 9.2 EUS | python-tornado +1 | 6.4.2-1.el9_2 | RHSA-2024:10836 |
| 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 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 |
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 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | tornado | < 6.4.1 | 6.4.1 | GHSA-753j-mpmx-qq6g |
Advisories 15
- WID-SEC-2026-4029 Red Hat Enterprise Linux (python-tornado, resteasy-core, bubblewrap, pgvector): Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- USN-8952-1 python-tornado vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 2026
- ALSA-2026:84798 Important: pcs security update AlmaLinux Security Advisories · Oct 29, 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-2025:2471 Red Hat Security Advisory: pcs security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2025:3108 Red Hat Security Advisory: pcs security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2025:2470 Red Hat Security Advisory: pcs security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2024:10836 Red Hat Security Advisory: python-tornado security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2024:10843 Red Hat Security Advisory: python-tornado security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2024:10590 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
References
- GitHub Security Advisory (GHSA-753j-mpmx-qq6g) vendor-advisory
- VulnCheck Advisory: Tornado before 6.4.1 HTTP Request Smuggling via Transfer-Encoding third-party-advisory