netty-codec-http2: Netty: Denial of Service via uncontrolled HTTP/2 concurrent streams (CVE-2026-47244)

Overview

A flaw was found in Netty, a network application framework. A remote attacker can exploit this vulnerability by sending a large number of HTTP/2 stream requests to a Netty HTTP/2 server. If the server does not explicitly limit concurrent streams, it can lead to the allocation of numerous long-lived stream objects. This excessive resource consumption can result in a denial of service (DoS), making the server unavailable to legitimate users.

Vendor advisories

• RHSA-2026:26018 · Red Hat · fixed in: Red Hat build of Quarkus 3.27.4.SP1 · released 2026-06-17 · advisory
• RHSA-2026:26017 · Red Hat · fixed in: Red Hat build of Quarkus 3.33.2.SP1 · released 2026-06-17 · advisory
• Red Hat VEX · Moderate · affected: Cryostat 4, OpenShift Serverless, Red Hat AMQ Broker 7, Red Hat build of Apache Camel - HawtIO 4, Red Hat build of Apache Camel 4 for Quarkus 3, Red Hat build of Apache Camel for Spring Boot 4, … · no fix planned: Cryostat 4, OpenShift Serverless, Red Hat AMQ Broker 7, Red Hat build of Apache Camel - HawtIO 4, … · updated 2026-10-20 · vex
• RHSA-2026:50085 · Red Hat · fixed in: Red Hat JBoss Enterprise Application Platform 8.1 · released 2026-08-04 · advisory

netty-codec-http2: Netty: Denial of Service via uncontrolled HTTP/2 concurrent streams — rated Moderate by Red Hat. Released 2026-06-12, updated 2026-10-20.

Affected:

• Cryostat 4
• OpenShift Serverless
• Red Hat AMQ Broker 7
• Red Hat build of Apache Camel - HawtIO 4
• Red Hat build of Apache Camel 4 for Quarkus 3
• Red Hat build of Apache Camel for Spring Boot 4
• Red Hat build of Apicurio Registry 3
• Red Hat build of Debezium 3
• Red Hat Build of Keycloak
• Red Hat Data Grid 8
• Red Hat Fuse 7
• Red Hat JBoss Enterprise Application Platform 7
• Red Hat JBoss Enterprise Application Platform Expansion Pack
• Red Hat OpenShift AI (RHOAI)
• Red Hat OpenShift Dev Spaces
• Red Hat Single Sign-On 7
• streams for Apache Kafka 2
• streams for Apache Kafka 3

Fixed:

• Red Hat build of Quarkus 3.27.4.SP1
• Red Hat build of Quarkus 3.33.2.SP1

No fix planned:

• Cryostat 4
• OpenShift Serverless
• Red Hat AMQ Broker 7
• Red Hat build of Apache Camel - HawtIO 4
• Red Hat build of Apache Camel 4 for Quarkus 3
• Red Hat build of Apache Camel for Spring Boot 4
• Red Hat build of Apicurio Registry 3
• Red Hat build of Debezium 3
• Red Hat Build of Keycloak
• Red Hat Data Grid 8
• Red Hat Fuse 7
• Red Hat JBoss Enterprise Application Platform 7
• Red Hat JBoss Enterprise Application Platform Expansion Pack
• Red Hat OpenShift AI (RHOAI)
• Red Hat OpenShift Dev Spaces
• Red Hat Single Sign-On 7
• streams for Apache Kafka 2
• streams for Apache Kafka 3

Not affected:

• Red Hat build of Quarkus 3.27.4.SP1
• Red Hat build of Quarkus 3.33.2.SP1
• Red Hat Enterprise Linux AI (RHEL AI) 3
• Red Hat OpenShift Dev Spaces

Remediation

Before applying this update, make sure all previously released errata relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:26018 Before applying this update, make sure all previously released errata relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:26017

Workarounds / mitigations:

• Configure affected applications using Netty HTTP/2 servers to explicitly set a maximum concurrent streams limit. Consult product-specific documentation for instructions on how to apply this configuration. Additionally, restrict network access to affected services to trusted clients and networks by implementing firewall rules or other network access controls. This may impact legitimate traffic if not carefully configured.

Package advisory (CVE-2026-47244)

Affected packages:

• io.netty:netty-codec-http2 >= 4.2.0.Final, <= 4.2.14.Final
• io.netty:netty-codec-http2 <= 4.1.134.Final

Patched in:

• io.netty:netty-codec-http2 4.2.15.Final
• io.netty:netty-codec-http2 4.1.135.Final

Source: https://github.com/advisories/GHSA-5x3r-wrvg-rp6q