# CVE-2021-43797: libnetty-java: Netty is an asynchronous event-driven network application framework forrapid development of maintainable high perform...

CVE-2021-43797 is fixed in 3 products on 1 platform, first by DEBIAN-CVE-2021-43797, released December 9, 2021. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-43797
- Priority: Routine
- CVSS: 6.5 (Medium)
- EPSS: 0.0288
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 9, 2021

## Description

Netty is an asynchronous event-driven network application framework forrapid development of maintainable high performance protocol servers &clients. Netty prior to version 4.1.71.Final skips control chars when theyare present at the beginning / end of the header name. It should insteadfail fast as these are not allowed by the spec and could lead to HTTPrequest smuggling. Failing to do the validation might cause netty to"sanitize" header names before it forward these to another remote systemwhen used as proxy. This remote system can't see the invalid usage anymore,and therefore does not do the validation itself. Users should upgrade toversion 4.1.71.Final.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libdb rocky 8 | 0:5.3.28-42.el8_4 | [RLSA-2022:5498](https://patchblox.com/security/data/fix/linux/rlsa-2022-5498.md) | Jul 5, 2022 |
| Linux | libnetty-java Ubuntu 18.04.6 LTS (bionic) | 1:4.1.7-4ubuntu0.1+esm2 | [libnetty-java 1:4.1.7-4ubuntu0.1+esm2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libnetty-java-1-4.1.7-4ubuntu0.1-esm2.md) | Dec 12, 2022 |
| Linux | libnetty-java Ubuntu 20.04 LTS (focal) | 1:4.1.45-1ubuntu0.1~esm1 | [libnetty-java 1:4.1.45-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libnetty-java-1-4.1.45-1ubuntu0.1-esm1.md) | Dec 12, 2022 |
| Linux | libnetty-java Ubuntu 22.04.1 LTS (jammy) | 1:4.1.48-4+deb11u1build0.22.04.1 | [libnetty-java 1:4.1.48-4+deb11u1build0.22.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libnetty-java-1-4.1.48-4-deb11u1build0.22.04.1.md) | Dec 12, 2022 |
| Linux | libnetty-java Ubuntu 24.10 (oracular) | 4.1.48-6 | [libnetty-java 4.1.48-6](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libnetty-java-4.1.48-6.md) | Jan 16, 2026 |
| Linux | libnetty-java Ubuntu 25.04 (plucky) | 4.1.48-6 | [libnetty-java 4.1.48-6](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libnetty-java-4.1.48-6.md) | Jan 16, 2026 |
| Linux | netty Debian 12.15 (bookworm) | 1:4.1.48-6 | [DEBIAN-CVE-2021-43797](https://patchblox.com/security/data/fix/linux/debian-cve-2021-43797.md) | Dec 9, 2021 |
| Linux | netty Debian 13.5 (trixie) | 1:4.1.48-6 | [DEBIAN-CVE-2021-43797](https://patchblox.com/security/data/fix/linux/debian-cve-2021-43797.md) | Dec 9, 2021 |
| Linux | netty Debian 14 | 1:4.1.48-6 | [DEBIAN-CVE-2021-43797](https://patchblox.com/security/data/fix/linux/debian-cve-2021-43797.md) | Dec 9, 2021 |

---

Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.