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Advisory severityHigh7.5Red Hat Linux

High [CVE-2026-55833] Denial of Service via SPDY header decompression amplification

This high-severity Red Hat Linux advisory covers CVE-2026-55833 affecting Cryostat 4 on RHEL 9, Red Hat AMQ Broker 7.13.6, Red Hat AMQ Broker 7.14.1.

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CVE-2026-55833 Source published Source updated

VulniPulse record published Record updated

CVE-2026-55833
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

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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 SPDY header decoding continues inflating zlib-compressed header blocks after the raw header parser has exceeded `maxHeaderSize` and marked the frame truncated in `SpdyFrameCodec`, allowing a remote peer to send a small compressed `HEADERS` block that expands into much larger raw header data and causes compression-amplified CPU and allocation churn.

By sending a specially crafted, small compressed header block, the attacker can cause it to expand significantly during decompression, leading to excessive CPU usage and memory allocation. This can result in a denial of service (DoS) due to resource exhaustion.

This is an Important denial of service vulnerability in Netty's SPDY header decoding. A remote, unauthenticated attacker can send a small, compressed SPDY header block that, during decompression, expands significantly beyond configured limits.

This leads to excessive CPU and memory consumption, potentially causing resource exhaustion and service unavailability in affected Red Hat products that utilize Netty with SPDY. Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Weakness: CWE-409.

Affected versions
  • < 4.1.136.Final
  • < 4.2.16.Final

Official advisory · high-confidence parse· fetched 1 day ago·verify at source

Fixed versions
  • 4.1.136
  • 4.2.16
  • cryostat/cryostat-reports-rhel9:4.2.0-14
  • cryostat/cryostat-rhel9:4.2.0-14
  • cryostat/jfr-datasource-rhel9:4.2.0-14
  • netty-codec-http
  • io.netty/netty-codec-http:4.1.136.Final-redhat-00001
  • eap8-activemq-artemis-0:2.40.0-8.redhat_00024.1.el10eap
  • eap8-apache-cxf-0:4.1.7-1.SP1_redhat_00001.1.el10eap
  • eap8-artemis-wildfly-integration-0:2.0.5-1.Final_redhat_00001.1.el10eap
  • eap8-bouncycastle-0:1.85.0-1.redhat_00001.1.el10eap
  • eap8-cryptacular-0:1.2.7-1.redhat_00002.1.el10eap
  • eap8-eap-product-conf-parent-0:801.8.0-1.GA_redhat_00001.1.el10eap
  • eap8-hibernate-0:6.6.54-1.Final_redhat_00001.1.el10eap
  • eap8-httpcomponents-asyncclient-0:4.1.5-5.redhat_00008.1.el10eap
  • eap8-ironjacamar-0:3.0.22-1.Final_redhat_00001.1.el10eap
  • eap8-jackson-annotations-0:2.18.9-1.redhat_00003.1.el10eap
  • eap8-jackson-core-0:2.18.9-1.redhat_00003.1.el10eap
  • eap8-jackson-databind-0:2.18.9-1.redhat_00003.1.el10eap
  • eap8-jackson-dataformats-text-0:2.18.9-1.redhat_00003.1.el10eap
  • eap8-jackson-jaxrs-providers-0:2.18.9-1.redhat_00003.1.el10eap
  • eap8-jackson-modules-base-0:2.18.9-1.redhat_00003.1.el10eap
  • eap8-jackson-modules-java8-0:2.18.9-1.redhat_00003.1.el10eap
  • eap8-jakarta-xml-bind-api-0:4.0.5-1.redhat_00001.1.el10eap
  • eap8-jaxb-0:4.0.7-4.redhat_00001.1.el10eap
  • eap8-jaxbintros-0:2.1.0-1.redhat_00001.1.el10eap
  • eap8-jboss-logging-0:3.6.3-1.Final_redhat_00001.1.el10eap
  • eap8-jboss-remoting-0:5.0.31-1.SP2_redhat_00001.1.el10eap
  • eap8-jbossws-api-0:3.1.0-1.Final_redhat_00001.1.el10eap
  • eap8-jbossws-common-tools-0:2.2.0-1.Final_redhat_00001.1.el10eap
  • eap8-jbossws-cxf-0:7.4.0-1.Final_redhat_00001.1.el10eap
  • eap8-jbossws-jaxws-undertow-httpspi-0:3.0.1-1.Final_redhat_00001.1.el10eap
  • eap8-jbossws-spi-0:5.1.0-1.Final_redhat_00001.1.el10eap
  • eap8-jsf-impl-0:4.0.11-2.SP1_redhat_00001.1.el10eap
  • eap8-log4j-0:2.25.4-1.redhat_00003.1.el10eap
  • eap8-neethi-0:3.2.2-1.redhat_00001.1.el10eap
  • eap8-netty-0:4.1.136-1.Final_redhat_00001.1.el10eap
  • eap8-netty-transport-native-epoll-0:4.1.136-1.Final_redhat_00001.1.el10eap
  • eap8-nimbus-jose-jwt-0:9.37.4-1.redhat_00001.1.el10eap
  • eap8-parsson-0:1.1.9-1.redhat_00001.1.el10eap
  • eap8-saaj-impl-0:3.0.6-1.redhat_00001.1.el10eap
  • eap8-slf4j-0:2.0.18-1.redhat_00001.1.el10eap
  • RHSA-2026:68333
  • RHSA-2026:66545
  • RHSA-2026:66488
  • RHSA-2026:54622
  • RHSA-2026:76637
  • RHSA-2026:50846
  • RHSA-2026:50848
  • RHSA-2026:47189

Official advisory · high-confidence parse· fetched 1 day ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Official advisory · high-confidence parse· fetched 1 day ago·verify at source

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