Description
h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| python-hyper | h11 | < 0.16.0 | — |
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-h11 | 0.14.0-1.1 | — |
| Debian 13 | python-h11 | 0.14.0-1.1 | — |
| Debian 12 | python-h11 | 0.14.0-1.1~deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | python-h11 | 0.14.0-1ubuntu0.24.04.1 | USN-7503-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat OpenStack 18 | python-h11 +1 | 0.12.0-4.el9ost | RHSA-2025:7535 |
| Red Hat OpenStack 17 | python-h11 +1 | 0.12.0-2.1.el9ost | RHSA-2025:7536 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP5 | python-h11 | 0.14.0-150400.9.6.1 | SUSE-SU-2025:1430-1 |
| SLES 15 SP4 | python-h11 | 0.14.0-150400.9.6.1 | SUSE-SU-2025:1430-1 |
| SLES 3 | python-h11 | 0.14.0-150400.9.6.1 | SUSE-SU-2025:1430-1 |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 SP5 | python-h11 | 0.14.0-150400.9.6.1 | SUSE-SU-2025:1430-1 |
| SLES for SAP 15 SP4 | python-h11 | 0.14.0-150400.9.6.1 | SUSE-SU-2025:1430-1 |
| SLE Micro 6.1 | python-h11 | 0.16.0-slfo.1.1_1.1 | SUSE-SU-2025:20330-1 |
| SLE Micro 6.1 | python-httpcore | 0.16.3-slfo.1.1_2.1 | SUSE-SU-2025:20330-1 |
| SLE Micro 6.0 | python-h11 | 0.16.0-1.1 | SUSE-SU-2025:20331-1 |
| SLE Micro 6.0 | python-httpcore | 0.16.3-7.1 | SUSE-SU-2025:20331-1 |
| SLE HPC 15 SP5 | python-h11 | 0.14.0-150400.9.6.1 | SUSE-SU-2025:1430-1 |
| SLE HPC 15 SP4 | python-h11 | 0.14.0-150400.9.6.1 | SUSE-SU-2025:1430-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-h11 | 0.16.0-1.1 | openSUSE-SU-2025:15032-1 |
| openSUSE Leap 15.6 | python-h11 | 0.14.0-150400.9.6.1 | SUSE-SU-2025:1430-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | airflow | 2.10.5-r43 | — |
| Wolfi rolling | checkov | 3.2.432-r0 | — |
| Wolfi rolling | jupyter-base-notebook | 7.4.1-r1 | — |
| Wolfi rolling | jupyter-docker-base +1 | 999.9.9_git20260925-r0 | — |
| Wolfi rolling | kserve +9 | 0.16.0-r5 | — |
| Wolfi rolling | kubeflow-pipelines-visualization-server | 2.4.1-r3 | — |
| Wolfi rolling | mitmproxy | 12.2.1-r0 | — |
| Wolfi rolling | reflex | 0.7.9-r0 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | h11 | < 0.16.0 | 0.16.0 | GHSA-vqfr-h8mv-ghfj |
Advisories 8
- RHSA-2025:7535 Red Hat Security Advisory: Red Hat OpenStack Platform 18.0 (python-h11) security update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- RHSA-2025:7536 Red Hat Security Advisory: Red Hat OpenStack Platform 17.1 (python-h11) security update Red Hat Security Advisories (RHSA) · Oct 16, 2026
- SUSE-SU-2025:20330-1 Security update for python-h11, python-httpcore SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:20331-1 Security update for python-httpcore, python-h11 SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:1430-1 Security update for python-h11 SUSE / openSUSE Security Updates · Mar 23, 2026
- USN-7503-1 python-h11 vulnerability Ubuntu Security Notices (USN) · Feb 10, 2026
- openSUSE-SU-2025:15032-1 python311-h11-0.16.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-1022 Red Hat OpenStack (python-h11): Schwachstelle ermöglicht Umgehen von Sicherheitsvorkehrungen BSI CERT-Bund (WID) · Aug 6, 2025