Description
Tornado before 6.3.3 contains an HTTP request smuggling vulnerability due to improper parsing of Content-Length headers accepting non-standard characters. Attackers can send crafted HTTP requests with these characters to bypass proxy validation and smuggle requests when deployed behind certain proxies.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| tornadoweb | tornado | < 6.3.3 | 6.3.3 |
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 | 6.4.0-1 | — |
| Debian 13 | python-tornado | 6.4.0-1 | — |
| 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 |
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 8 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| 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 |
| 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 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | tornado | < 6.3.3 | 6.3.3 | GHSA-qppv-j76h-2rpx |
Advisories 3
- USN-8952-1 python-tornado vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 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-qppv-j76h-2rpx) vendor-advisory
- VulnCheck Advisory: Tornado before 6.3.3 HTTP Request Smuggling via Content-Length third-party-advisory