Description
Tornado versions before 6.5.9 contain an unbounded memory accumulation vulnerability in CurlAsyncHTTPClient that allows remote attackers to cause denial of service by sending a compressed response. Attackers can send a gzip-encoded decompression bomb that accumulates in memory without size limits, causing the application process to be killed by out-of-memory conditions.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| tornadoweb | tornado | < 6.5.9 | 6.5.9 |
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 | 6.5.10-1.el10_2.1 | RHSA-2026:82041 |
| RHEL 9 | python-tornado +1 | 6.5.10-1.el9_8.1 | RHSA-2026:82040 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | python3-tornado | 6.5.10-1.el10_2.1 | ALSA-2026:82041 |
| AlmaLinux 9 | python3-tornado | 6.5.10-1.el9_8.1 | ALSA-2026:82040 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | python-tornado | 6.5.10-1.el10_2.1 | RLSA-2026:82041 |
| Rocky Linux 10 | python3-tornado | 6.5.10-1.el10_3 | RLSA-2026:98080 |
| Rocky Linux 9 | python-tornado | 6.5.10-1.el9_8.1 | RLSA-2026:98473, RLSA-2026:82040 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | python3-tornado +1 | 6.1.0-2.amzn2023.0.12 | ALAS2023-2026-3292 |
| Amazon Linux 2023 | python3.13-tornado +1 | 6.4.2-1.amzn2023.0.7 | ALAS2023-2026-3293 |
| Amazon Linux 2 | python-tornado +1 | 4.2.1-3.amzn2.0.9 | ALAS2-2026-4011 |
| Amazon Linux 2 | python3-tornado +1 | 5.0.2-4.amzn2.0.12 | ALAS2-2026-4033 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | python-tornado | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | python3-tornado | 6.5.10-1.el10_2.1 | ELSA-2026-82041 |
| Oracle Linux 9 | python3-tornado | 6.5.10-1.el9_8.1 | ELSA-2026-82040 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | tornado | < 6.5.9 | 6.5.9 | GHSA-chx6-46f5-w4vp |
Advisories 17
- RLSA-2026:98080 Important: python-tornado security update Rocky Linux Security Advisories · Nov 13, 2026
- WID-SEC-2026-4111 Red Hat Ansible Automation Platform: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- RLSA-2026:98473 Important: python-tornado security update Rocky Linux Security Advisories · Nov 12, 2026
- WID-SEC-2026-3883 Red Hat Enterprise Linux (goose, environment-modules, tornado): Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- USN-8952-1 python-tornado vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 2026
- ALSA-2026:82040 Important: python-tornado security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:82041 Important: python-tornado security update AlmaLinux Security Advisories · Oct 29, 2026
- ALAS2023-2026-3292 Important: python-tornado security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 26, 2026
- ALAS2023-2026-3293 Important: python3.13-tornado security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 26, 2026
- ALAS2-2026-4011 Important: python-tornado security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 26, 2026
- ALAS2-2026-4033 Important: python3-tornado security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 26, 2026
- RHSA-2026:82041 Red Hat Security Advisory: python-tornado security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:82040 Red Hat Security Advisory: python-tornado security update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RLSA-2026:82041 Important: python-tornado security update Rocky Linux Security Advisories · Oct 14, 2026
- RLSA-2026:82040 Important: python-tornado security update Rocky Linux Security Advisories · Oct 14, 2026
- ELSA-2026-82040 Important: python-tornado security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 13, 2026
- ELSA-2026-82041 Important: python-tornado security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Oct 13, 2026