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.

Routine
CVSS
n/a
Medium
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0494
92nd percentile

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

ProductFixed inFixReleased
Linux
libdb · rocky 8 0:5.3.28-42.el8_4 RLSA-2022:5498 Jul 5, 2022
libnetty-java · Ubuntu 18.04.6 LTS (bionic) 1:4.1.7-4ubuntu0.1+esm2 libnetty-java 1:4.1.7-4ubuntu0.1+esm2 Dec 12, 2022
libnetty-java · Ubuntu 20.04 LTS (focal) 1:4.1.45-1ubuntu0.1~esm1 libnetty-java 1:4.1.45-1ubuntu0.1~esm1 Dec 12, 2022
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 Dec 12, 2022
libnetty-java · Ubuntu 24.10 (oracular) 4.1.48-4 libnetty-java 4.1.48-4 Jan 16, 2026
libnetty-java · Ubuntu 25.04 (plucky) 4.1.48-4 libnetty-java 4.1.48-4 Jan 16, 2026

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