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Fencer Vulns
high 7.5

CVE-2026-55831 json

Netty SPDY SETTINGS frame count materializes unbounded settings map

published 2026-07-20 3 mo ago modified 2026-09-10 1 mo ago also GHSA-6jqx-86gh-f27w , EUVD-2026-46132

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

Summary

Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty's SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in `DefaultSpdySettingsFrame`, allowing a remote SPDY/3.1 peer to send a syntactically valid roughly 2 MiB SETTINGS frame that creates 262144 map entries and amplifies network input into heap growth and ordered-map insertion work. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Patch / fix

  • maven io.netty:netty-codec-http 4.1.136.Final, 4.2.16.Final
  • netty netty 4.1.136, 4.2.16
  • eap8-jaxb jboss enterprise application platform 8.1 4.0.7-4.redhat_00001.1.el10eap
  • eap8-txw2 jboss enterprise application platform 8.1 4.0.7-4.redhat_00001.1.el10eap
  • eap8-xsom jboss enterprise application platform 8.1 4.0.7-4.redhat_00001.1.el10eap
  • eap8-log4j jboss enterprise application platform 8.1 2.25.4-1.redhat_00003.1.el10eap
  • eap8-netty jboss enterprise application platform 8.1 4.1.136-1.Final_redhat_00001.1.el10eap
  • eap8-rngom jboss enterprise application platform 8.1 4.0.7-4.redhat_00001.1.el10eap
  • eap8-slf4j jboss enterprise application platform 8.1 2.0.18-1.redhat_00001.1.el10eap
  • eap8-neethi jboss enterprise application platform 8.1 3.2.2-1.redhat_00001.1.el10eap

red hat advisories RHSA-2026:70230RHSA-2026:70229RHSA-2026:70228

  • netty-tcnative SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.0.80-150200.3.48.1
  • netty SLE Module for Package Hub 15 SP7 4.1.136-150200.4.53.1

suse advisories SUSE-SU-2026:3482-1

  • netty openSUSE Tumbleweed 4.1.136-1.1

opensuse advisories openSUSE-SU-2026:11394-1

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-2026-55831 updated cvss 7.5

io.netty/netty-codec-http: Netty: Denial of Service via SPDY SETTINGS frame processing

  • 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 Clients netty-codec-http 4.1.130.Final-redhat-00001 Red Hat build of Apache Camel - HawtIO 4 netty-codec-http 4.1.130.Final-redhat-00001 Red Hat build of Apache Camel 4 for Quarkus 3 netty-codec-http 4.1.130.Final-redhat-00001
    affected: workaround, no fix available
  • Red Hat build of Debezium 3 netty-codec-http 4.1.130.Final-redhat-00001
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Build of Keycloak rhbk-keycloak-rhel9, rhbk-rhel9-operator, rhbk-openshift-rhel9, rhbk-keycloak-rhel9-operator, netty-codec-http 4.1.130.Final-redhat-00001
    affected: workaround, no fix available
  • Red Hat build of Quarkus netty-codec-http 4.1.130.Final-redhat-00001
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux AI (RHEL AI) 3 bazel6 6.5.0-2.el9ai, bazel7 7.7.1-1.el9ai, bazel8 8.6.0-1.el9ai
    affected: workaround, no fix available
  • Red Hat JBoss Enterprise Application Platform 7 eap74-els-openjdk8-openshift-rhel8, eap74-els-openjdk11-openshift-rhel8, eap74-els-openjdk17-openshift-rhel8, netty-codec-http 4.1.130.Final-redhat-00001, jboss-eap-7-eap74-els-openjdk8-openshift-rhel8, jboss-eap-7-eap74-els-openjdk17-openshift-rhel8
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-th06-cpu-torch291-py312-rhel9, rhoai/odh-th06-cuda130-torch291-py312-rhel9
    affected: workaround, no fix available
  • Red Hat Single Sign-On 7 netty-codec-http 4.1.130.Final-redhat-00001
    affected: workaround, no fix available “Fix deferred”
show 24 more
  • Red Hat Cryostat 4 on RHEL 9 cryostat/cryostat-rhel9 4.2.0-14, cryostat/jfr-datasource-rhel9 4.2.0-14, cryostat/cryostat-reports-rhel9 4.2.0-14
    fixed: vendor fix RHSA-2026:68333
  • Red Hat AMQ Broker 7.13.6
    fixed: vendor fix RHSA-2026:66545
  • Red Hat AMQ Broker 7.14.1
    fixed: vendor fix RHSA-2026:66488
  • Red Hat Build of Apache Camel 3.33.2.SP3 netty-codec-http 4.1.136.Final-redhat-00001
    fixed: vendor fix RHSA-2026:48118
  • Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16
    fixed: vendor fix RHSA-2026:54622
  • Red Hat build of Apicurio Registry 3.3.3
    fixed: vendor fix RHSA-2026:76637
  • Red Hat build of Keycloak 26.4.14
    fixed: vendor fix RHSA-2026:50846
  • Red Hat build of Keycloak 26.6.5
    fixed: vendor fix RHSA-2026:50848
  • Red Hat build of Quarkus 3.27.4.SP3 netty-codec-http 4.1.136.Final-redhat-00001
    fixed: vendor fix RHSA-2026:47189
  • Red Hat build of Quarkus 3.33.2.SP3 netty-codec-http 4.1.136.Final-redhat-00001
    fixed: vendor fix RHSA-2026:47172
  • Red Hat Data Grid 8.6.3
    fixed: vendor fix RHSA-2026:69296
  • Red Hat JBoss EAP 8.1 for RHEL 8 eap8-jaxb 4.0.7-4.redhat_00001.1.el8eap, eap8-txw2 4.0.7-4.redhat_00001.1.el8eap, eap8-xsom 4.0.7-4.redhat_00001.1.el8eap, eap8-rngom 4.0.7-4.redhat_00001.1.el8eap, eap8-log4j 2.25.4-1.redhat_00003.1.el8eap, eap8-neethi 3.2.2-1.redhat_00001.1.el8eap, +101 more
    fixed: vendor fix RHSA-2026:70228
  • Red Hat JBoss EAP 8.1 for RHEL 9 eap8-jaxb 4.0.7-4.redhat_00001.1.el9eap, eap8-txw2 4.0.7-4.redhat_00001.1.el9eap, eap8-xsom 4.0.7-4.redhat_00001.1.el9eap, eap8-rngom 4.0.7-4.redhat_00001.1.el9eap, eap8-log4j 2.25.4-1.redhat_00003.1.el9eap, eap8-neethi 3.2.2-1.redhat_00001.1.el9eap, +101 more
    fixed: vendor fix RHSA-2026:70229
  • Red Hat JBoss EAP 8.1 for RHEL 10 eap8-jaxb 4.0.7-4.redhat_00001.1.el10eap, eap8-txw2 4.0.7-4.redhat_00001.1.el10eap, eap8-xsom 4.0.7-4.redhat_00001.1.el10eap, eap8-rngom 4.0.7-4.redhat_00001.1.el10eap, eap8-log4j 2.25.4-1.redhat_00003.1.el10eap, eap8-neethi 3.2.2-1.redhat_00001.1.el10eap, +100 more
    fixed: vendor fix RHSA-2026:70230
  • Red Hat JBoss Enterprise Application Platform 8.1.8.GA netty-codec-http 4.1.136.Final-redhat-00001
    fixed: vendor fix RHSA-2026:70277
  • Red Hat OpenShift AI 2.25 rhoai/odh-modelmesh-rhel9 1790881700, rhoai/odh-trustyai-service-rhel9 1788198681
    fixed: vendor fix RHSA-2026:87410
  • Red Hat OpenShift AI 3.4 rhoai/odh-trustyai-service-rhel9 1791792525, rhoai/odh-th06-cpu-torch210-py312-rhel9 1791874335, rhoai/odh-th06-rocm64-torch291-py312-rhel9 1791872119, rhoai/odh-th06-cuda130-torch210-py312-rhel9 1791961113
    fixed: vendor fix RHSA-2026:84734
  • Red Hat OpenShift Dev Spaces 3.30 devspaces/server-rhel9 1789163798, devspaces/openvsx-rhel9 1787759145, devspaces/pluginregistry-rhel9 1787759723
    fixed: vendor fix RHSA-2026:62260
  • Red Hat OpenShift Dev Spaces 3.31 devspaces/jetbrains-ide-rhel9 1792476427, devspaces/multicluster-redirector-rhel9 1792491532
    fixed: vendor fix RHSA-2026:90321
  • Red Hat Streams for Apache Kafka 3.2.1
    fixed: vendor fix RHSA-2026:54435
  • Red Hat Cryostat 4 on RHEL 9 cryostat/cryostat-db-rhel9 4.2.0-22, cryostat/cryostat-storage-rhel9 4.2.0-22, cryostat/cryostat-rhel9-operator 4.2.0-21, cryostat/cryostat-operator-bundle 4.2.0-12, cryostat/cryostat-agent-init-rhel9 0.7.0-12, cryostat/cryostat-grafana-dashboard-rhel9 4.2.0-14, +1 more Red Hat Build of Apache Camel 3.33.2.SP3 jimfs 1.1, jna 5.8.0, bcel 6.7.0, bson 5.6.4, gax 2.74.1, icu4j 78.2, +1630 more Red Hat build of Quarkus 3.27.4.SP3 jna 5.8.0, db2 1.21.4, h2 2.3.230, y18n 5.0.8, cliui 8.0.1, guice 5.1.0, +1009 more Red Hat build of Quarkus 3.33.2.SP3 jna 5.8.0, bson 5.6.4, h2 2.4.240, y18n 5.0.8, cliui 8.0.1, guice 5.1.0, +1018 more Red Hat JBoss Enterprise Application Platform 8.1.8.GA pom.xml, aesh 2.4, c3 0.6.4, d3 7.4.3, he 1.2.0, lr 1.4.2, +1868 more
    not affected: vulnerable code not present
  • Red Hat JBoss Enterprise Application Platform Expansion Pack netty-codec-http 4.1.130.Final-redhat-00001
    not affected: component not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-spark-operator-rhel9
    not affected: vulnerable code not in execute path
  • Red Hat OpenShift AI 2.25 rhoai/odh-rhel9-operator 1788331391, rhoai/odh-rhel9-operator 1792570619, rhoai/odh-vllm-cpu-rhel9 1786712073, rhoai/odh-vllm-cpu-rhel9 1792018436, rhoai/odh-dashboard-rhel9 1788312226, rhoai/odh-dashboard-rhel9 1791853525, +141 more Red Hat OpenShift AI 3.4 rhoai/odh-cli-rhel9 1791509689, rhoai/rhai-cli-rhel9 1791509689, rhoai/odh-automl-rhel9 1791535789, rhoai/odh-mlflow-rhel9 1791865967, rhoai/odh-autorag-rhel9 1791557539, rhoai/odh-trainer-rhel9 1791869783, +96 more
    not affected: vulnerable code not present

4 more not affected in the full advisory

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
3 mo ago

Exploit prediction

0.66% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/netty/netty/security/advisories/GHSA-6jqx-86gh-f27w referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
maven io.netty:netty-codec-http
>=4.2.0.Final, <4.2.16.Final
>=4.1.0.Final, <4.1.136.Final
4.2.16.Final
4.1.136.Final

Affected products

  • netty netty

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling
  • CWE-400 Uncontrolled Resource Consumption

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.