Description
Netty versions 4.1.133.Final through 4.1.137.Final and 4.2.13.Final through 4.2.17.Final fail to properly validate the final transfer coding in the Transfer-Encoding header, allowing attackers to smuggle requests by using malformed encoding declarations. Attackers can split Transfer-Encoding headers across multiple lines or use values like 'chunked, xchunked' to bypass validation and decode messages as chunked when the final coding is not chunked, enabling request smuggling attacks.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| netty | netty | 4.1.133.Final – < 4.1.138.Final, 4.2.13.Final – < 4.2.18.Final | 4.1.138.Final |
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 | netty | No fix yet | — |
| Debian 13 | netty | No fix yet | — |
| Debian 12 | netty | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | netty | No fix yet | — |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | netty | No fix yet | — |
| Ubuntu Pro 24.04 LTS | netty | No fix yet | — |
| Ubuntu Pro 22.04 LTS | netty | No fix yet | — |
| Ubuntu Pro 20.04 LTS | netty | No fix yet | — |
| Ubuntu Pro 18.04 LTS | netty | No fix yet | — |
| Ubuntu Pro 16.04 LTS | netty | No fix yet | — |
| Ubuntu Pro 14.04 LTS | netty | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | netty | 4.1.138-150200.4.56.1 | SUSE-SU-2026:4391-1 |
| SLES 15 SP7 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
| SLES 15 SP6 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
| SLES 15 SP5 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
| SLES 15 SP4 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 SP6 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
| SLES for SAP 15 SP5 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
| SLES for SAP 15 SP4 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
| SLE HPC 15 SP5 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
| SLE HPC 15 SP4 | netty-tcnative | 2.0.84-150200.3.51.1 | SUSE-SU-2026:4391-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | netty | 4.1.138-1.1 | openSUSE-SU-2026:11882-1 |
Advisories 3
- WID-SEC-2026-3291 Netty: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 8, 2026
- SUSE-SU-2026:4391-1 Security update for netty, netty-tcnative SUSE / openSUSE Security Updates · Sep 30, 2026
- openSUSE-SU-2026:11882-1 netty-4.1.138-1.1 on GA media SUSE / openSUSE Security Updates · Sep 25, 2026
References
- GitHub Security Advisory (GHSA-hcvj-94mj-jp5c) vendor-advisory
- Fix commit on the 4.1 branch: match the final transfer-coding token exactly patch
- Fix commit on the 4.2 branch patch
- Suffix-based chunked-must-be-last check at netty-4.1.137.Final technical-description
- netty netty-4.1.138.Final Release Notes release-notes
- netty netty-4.2.18.Final Release Notes release-notes
- netty/netty product
- VulnCheck Advisory: Netty 4.1.133.Final through 4.1.137.Final and 4.2.13.Final through 4.2.17.Final HTTP Request Smuggling via Transfer-Encoding third-party-advisory