Description
Gunicorn version 21.2.0 does not properly validate the value of the 'Transfer-Encoding' header as specified in the RFC standards, which leads to the default fallback method of 'Content-Length,' making it vulnerable to TE.CL request smuggling. This vulnerability can lead to cache poisoning, data exposure, session manipulation, SSRF, XSS, DoS, data integrity compromise, security bypass, information leakage, and business logic abuse.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| benoitc | benoitc/gunicorn | unspecified – ≤ latest | — |
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 | gunicorn | 23.0.0-1 | — |
| Debian 13 | gunicorn | 23.0.0-1 | — |
| Debian 12 | gunicorn | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | gunicorn | No fix yet | — |
| Ubuntu 26.04 LTS | gunicorn | No fix yet | — |
| Ubuntu 25.10 | gunicorn | No fix yet | — |
| Ubuntu 24.04 LTS | gunicorn | No fix yet | — |
| Ubuntu 22.04 LTS | gunicorn | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | gunicorn | No fix yet | — |
| Ubuntu 18.04 LTS | gunicorn | No fix yet | — |
| Ubuntu 16.04 LTS | gunicorn | No fix yet | — |
| Ubuntu Pro 14.04 LTS | gunicorn | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP6 | python-gunicorn | 19.7.1-150000.3.10.1 | SUSE-SU-2025:1002-1 |
| SLES 15 SP5 | python-gunicorn | 19.7.1-150000.3.10.1 | SUSE-SU-2025:1008-1, SUSE-SU-2025:1002-1 |
| SLES 15 SP4 | python-gunicorn | 19.7.1-150000.3.10.1 | SUSE-SU-2025:1008-1, SUSE-SU-2025:1002-1 |
| SLES 15 SP3 | python-gunicorn | 19.7.1-150000.3.10.1 | SUSE-SU-2025:1002-1 |
| SLES 3 | python-gunicorn | 20.1.0-150400.12.9.1 | SUSE-SU-2025:1008-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 SP5 | python-gunicorn | 20.1.0-150400.12.9.1 | SUSE-SU-2025:1008-1 |
| SLES for SAP 15 SP4 | python-gunicorn | 20.1.0-150400.12.9.1 | SUSE-SU-2025:1008-1 |
| SLE HPC 15 SP5 | python-gunicorn | 20.1.0-150400.12.9.1 | SUSE-SU-2025:1008-1 |
| SLE HPC 15 SP4 | python-gunicorn | 20.1.0-150400.12.9.1 | SUSE-SU-2025:1008-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.6 | python-gunicorn | 20.1.0-150400.12.9.1 | SUSE-SU-2025:1008-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | emissary +6 | 3.9.1-r14 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | gunicorn | < 22.0.0 | 22.0.0 | GHSA-hc5x-x2vx-497g |
Advisories 3
- SUSE-SU-2025:1008-1 Security update for python-gunicorn SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2025:1002-1 Security update for python-gunicorn SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-0998 IBM App Connect Enterprise Certified Container: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 6, 2025