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Fencer Vulns
medium 5.3

CVE-2026-47244 json

Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced

published 2026-06-08 5 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-36455 , GHSA-5x3r-wrvg-rp6q

cvss
5.3
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 32%
public exploits
0
none known

Summary

Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, DefaultHttp2Connection.DefaultEndpoint initialises maxActiveStreams/maxStreams to Integer.MAX_VALUE, and Http2Settings never inserts SETTINGS_MAX_CONCURRENT_STREAMS by default (Http2Settings.java:305-307 only clamps a user-supplied value). Unless the application explicitly calls initialSettings().maxConcurrentStreams(n), a Netty HTTP/2 server advertises no limit and enforces none locally. Each open stream allocates a DefaultStream object, PropertyMap slots, flow-controller state and IntObjectHashMap entry; with ~2^30 permissible odd stream IDs a single TCP connection can create hundreds of thousands of long-lived stream objects. This is also the precondition for CVE-2023-44487-style Rapid-Reset amplification, where the absence of a low concurrent cap multiplies backend work. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Patch / fix

  • maven io.netty:netty-codec-http2 4.1.135.Final, 4.2.15.Final
  • io.netty netty-codec-http2 4.1.135.Final, 4.2.15.Final
  • netty netty 4.1.135.Final, 4.2.15.Final
  • netty-tcnative SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.0.79-150200.3.45.1
  • netty SLE Module for Package Hub 15 SP7 4.1.135-150200.4.50.1

suse advisories SUSE-SU-2026:2802-1

  • netty openSUSE Tumbleweed 4.1.135-1.1

opensuse advisories openSUSE-SU-2026:11033-1

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-2026-47244 updated cvss 5.3

netty-codec-http2: Netty: Denial of Service via uncontrolled HTTP/2 concurrent streams

  • Red Hat Cryostat 4 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-http2 Red Hat build of Apache Camel - HawtIO 4 netty-codec-http2 Red Hat build of Apache Camel 4 for Quarkus 3 netty-codec-http2 Red Hat build of Apache Camel for Spring Boot 4 netty-codec-http2
    +12 more products
    Red Hat build of Apicurio Registry 3 netty-codec-http2 Red Hat build of Debezium 3 netty-codec-http2 Red Hat Build of Keycloak netty-codec-http2, rhbk-rhel9-operator, rhbk/keycloak-rhel9, rhbk-openshift-rhel9, rhbk/keycloak-rhel9-operator Red Hat Data Grid 8 netty-codec-http2 Red Hat Fuse 7 netty-codec-http2 Red Hat JBoss Enterprise Application Platform 7 netty-codec-http2 Red Hat JBoss Enterprise Application Platform Expansion Pack netty-codec-http2 Red Hat OpenShift AI (RHOAI) rhoai/odh-modelmesh-rhel9, rhoai/odh-spark-operator-rhel9, rhoai/odh-trustyai-service-rhel9, rhoai/odh-openvino-model-server-rhel9, rhoai/odh-th06-cpu-torch210-py312-rhel9, rhoai/odh-th06-cpu-torch291-py312-rhel9, +3 more Red Hat OpenShift Dev Spaces devspaces/openvsx-rhel9, devspaces/jetbrains-ide-rhel9, devspaces/pluginregistry-rhel9, devspaces/multicluster-redirector-rhel9 Red Hat Single Sign-On 7 netty-codec-http2 Red Hat streams for Apache Kafka 2 netty-codec-http2 Red Hat streams for Apache Kafka 3 netty-codec-http2
    affected: workaround, no fix available “Fix deferred”
  • Red Hat build of Quarkus 3.27.4.SP1 netty-codec-http2 4.1.135.Final-redhat-00001
    fixed: vendor fix RHSA-2026:26018
  • Red Hat build of Quarkus 3.33.2.SP1 netty-codec-http2 4.1.135.Final-redhat-00001
    fixed: vendor fix RHSA-2026:26017
  • Red Hat build of Quarkus 3.27.4.SP1 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.SP1 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 Enterprise Linux AI (RHEL AI) 3 bazel6, bazel7, bazel8 Red Hat OpenShift Dev Spaces devspaces/server-rhel9
    not affected: vulnerable code not present

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
none
Automatable
yes
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
maven io.netty:netty-codec-http2
>=4.2.0.Final, <4.2.15.Final
<4.1.135.Final
4.2.15.Final
4.1.135.Final

Affected products

  • netty netty

Classification

Weakness
  • 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.

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