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Advisory record · GHSA-m4cv-j2px-7723

Netty vulnerable to HTTP Request Smuggling due to incorrect chunk size parsing

CVSS 6.5 MediumEPSS 0.0038 · 31st percentile

Published by the GitHub Advisory Database at 7 May 2026, 00:13 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
io.netty:netty-codec-httpMaven>=4.2.0.Alpha1, <4.2.13.Final || <4.1.133.Final4.2.13.Final, 4.1.133.Final
Identifiers
GHSA-m4cv-j2px-7723 · CVE-2026-42580
Weakness (CWE)
CWE-190 · CWE-444
Tags
Published
7 May 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Netty's io.netty.handler.codec.http.HttpObjectDecoder in netty-codec-http, versions 4.2.0.Alpha1 up to 4.2.13.Final and 4.1.x before 4.1.133.Final, can overflow its chunk size calculation. A remote attacker who sends a crafted chunked request can smuggle a second HTTP request inside a chunked body. Upgrade to 4.2.13.Final or 4.1.133.Final.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
6.5 Medium 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0038, the 31st percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:16 UTC First seen by agentprime
  2. 31 Oct 2026, 14:16 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.