# CVE-2021-21409: libnetty-java: Netty is an open-source, asynchronous event-driven network applicationframework for rapid development of maintainable...

CVE-2021-21409 is fixed in 2 products on 1 platform, first by RLSA-2022:5498, released July 5, 2022. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-21409
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.0494
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 30, 2021

## Description

Netty is an open-source, asynchronous event-driven network applicationframework for rapid development of maintainable high performance protocolservers & clients. In Netty (io.netty:netty-codec-http2) before version4.1.61.Final there is a vulnerability that enables request smuggling. Thecontent-length header is not correctly validated if the request only uses asingle Http2HeaderFrame with the endStream set to to true. This could leadto request smuggling if the request is proxied to a remote peer andtranslated to HTTP/1.1. This is a followup ofGHSA-wm47-8v5p-wjpj/CVE-2021-21295 which did miss to fix this one case.This was fixed as part of 4.1.61.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) | 4.1.48-4 | [libnetty-java 4.1.48-4](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libnetty-java-4.1.48-4.md) | Jan 16, 2026 |
| Linux | libnetty-java Ubuntu 25.04 (plucky) | 4.1.48-4 | [libnetty-java 4.1.48-4](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libnetty-java-4.1.48-4.md) | Jan 16, 2026 |

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Data as of 2026-11-08T19:12:23Z 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

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