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Fencer Vulns
medium 6.5

CVE-2026-42580 json

Netty: HTTP Request Smuggling due to incorrect chunk size parsing

published 2026-05-07 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-30123 , GHSA-m4cv-j2px-7723

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's chunk size parser silently overflows int, enabling request smuggling attacks. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Patch / fix

  • maven io.netty:netty-codec-http 4.1.133.Final, 4.2.13.Final
  • netty netty 4.1.133.Final, 4.2.13.Final
  • io.netty netty-codec-http 4.1.133.Final, 4.2.13.Final
  • netty-tcnative SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.0.77-150200.3.39.1
  • netty SLE Module for Package Hub 15 SP7 4.1.133-150200.4.46.1

suse advisories SUSE-SU-2026:2308-1

  • netty openSUSE Tumbleweed 4.1.133-1.1

opensuse advisories openSUSE-SU-2026:10795-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-42580 updated cvss 6.5

netty: Netty: Request smuggling via chunk size parser integer overflow

  • Red Hat Cryostat 4 netty-codec-http, netty-codec-http2 Red Hat OpenShift Serverless openshift-serverless-1/kn-ekb-receiver-rhel9, openshift-serverless-1/kn-ekb-dispatcher-rhel9, openshift-serverless-1/kn-eventing-integrations-log-sink-rhel9, openshift-serverless-1/kn-eventing-integrations-aws-s3-sink-rhel9, openshift-serverless-1/kn-eventing-integrations-aws-sns-sink-rhel9, openshift-serverless-1/kn-eventing-integrations-aws-sqs-sink-rhel9, +4 more Red Hat AMQ Broker 7 netty-codec-http, netty-codec-http2 Red Hat AMQ Clients netty-codec-http Red Hat build of Apache Camel 4 for Quarkus 3 netty-codec-http, netty-codec-http2 Red Hat build of Apache Camel for Spring Boot 4 netty-codec-http, netty-codec-http2
    +19 more products
    Red Hat build of Apicurio Registry 2 netty-codec-http, netty-codec-http2 Red Hat build of Apicurio Registry 3 netty-codec-http, netty-codec-http2 Red Hat build of Debezium 3 netty-codec-http, netty-codec-http2 Red Hat Build of Keycloak netty-codec-http, netty-codec-http2, rhbk-rhel9-operator, rhbk/keycloak-rhel9, rhbk-openshift-rhel9, rhbk/keycloak-rhel9-operator Red Hat build of OptaPlanner 8 netty-codec-http, netty-codec-http2 Red Hat build of Quarkus netty-codec-http, netty-codec-http2 Red Hat Data Grid 8 netty-codec-http, netty-codec-http2 Red Hat Enterprise Linux AI (RHEL AI) 3 bazel6, bazel7, bazel8 Red Hat Fuse 7 netty-codec-http, netty-codec-http2 Red Hat JBoss Enterprise Application Platform 7 netty-codec-http, netty-codec-http2 Red Hat JBoss Enterprise Application Platform 8 netty-codec-http Red Hat JBoss Enterprise Application Platform Expansion Pack netty-codec-http, netty-codec-http2 Red Hat OpenShift AI (RHOAI) rhoai/odh-modelmesh-rhel8, rhoai/odh-modelmesh-rhel9, rhoai/odh-spark-operator-rhel9, rhoai/odh-trustyai-service-rhel8, rhoai/odh-trustyai-service-rhel9, rhoai/odh-th06-cpu-torch210-py312-rhel9, +4 more Red Hat OpenShift Dev Spaces devspaces/server-rhel9, devspaces/openvsx-rhel9, devspaces/pluginregistry-rhel9, devspaces/multicluster-redirector-rhel9 Red Hat Process Automation 7 netty-codec-http, netty-codec-http2 Red Hat Satellite 6 candlepin, candlepin-selinux Red Hat Single Sign-On 7 netty-codec-http, netty-codec-http2 Red Hat streams for Apache Kafka 2 netty-codec-http, netty-codec-http2 Red Hat streams for Apache Kafka 3 netty-codec-http, netty-codec-http2
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/netty/netty/security/advisories/GHSA-m4cv-j2px-7723 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Affected packages

ecosystem package affected fixed in
maven io.netty:netty-codec-http
>=4.2.0.Alpha1, <4.2.13.Final
<4.1.133.Final
4.2.13.Final
4.1.133.Final

Affected products

  • netty netty
  • io.netty netty-codec-http

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.