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TI-2026-40313 Aliases CVE-2026-55851GHSA-q6cq-mhr2-jmr5

Netty codec-haproxy: Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbounded Memory Exhaustion

Priority MEDIUM 45CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 12 fixed, 10 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final up to (but not including) 4.2.16.Final, and 4.1.0.Final up to (but not including) 4.1.135, the `HAProxyMessageDecoder` in Netty's `codec-haproxy` module performs protocol version detection by reading the 13th byte as a signed Java `byte` and widening it to `int` without masking; a PROXY protocol v2 binary prefix followed by version byte `0xFF` sign-extends to `-1`, collides with the decoder's need-more-data sentinel, and causes `ByteToMessageDecoder` to accumulate inbound bytes in an unbounded `cumulation` buffer until direct memory is exhausted. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0063 50th percentileScored 2026-11-07
Fix Partial netty (netty): 4.2.16.Final, 4.1.136.Finalio.netty:netty-codec-haproxy (Maven): 4.2.16.Final, 4.1.136.FinalRed Hat: 12 advisoriesRed Hat: 12 fixed, 10 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
nettynetty4.2.0.Final to before 4.2.16.Final; 4.1.0.Final to before 4.1.136.Final4.2.16.Final, 4.1.136.FinalPatch availableCNA
—io.netty:netty-codec-haproxy (Maven)4.2.0.Final to before 4.2.16.Final4.2.16.FinalPatch availableGHSA-q6cq-mhr2-jmr5
—io.netty:netty-codec-haproxy (Maven)4.1.0.Final to before 4.1.136.Final4.1.136.FinalPatch availableGHSA-q6cq-mhr2-jmr5
  • netty Vendornetty Affected 4.2.0.Final to before 4.2.16.Final; 4.1.0.Final to before 4.1.136.Final Fixed in 4.2.16.Final, 4.1.136.Final Patch available CNA
  • io.netty:netty-codec-haproxy (Maven) Vendor— Affected 4.2.0.Final to before 4.2.16.Final Fixed in 4.2.16.Final Patch available GHSA-q6cq-mhr2-jmr5
  • io.netty:netty-codec-haproxy (Maven) Vendor— Affected 4.1.0.Final to before 4.1.136.Final Fixed in 4.1.136.Final Patch available GHSA-q6cq-mhr2-jmr5

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*4.1.0 to before 4.1.136; 4.2.0 to before 4.2.16Vulnerablenetty
  • cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:* Versions 4.1.0 to before 4.1.136; 4.2.0 to before 4.2.16 Vulnerable ·netty

Remediation

  • Fix · CNA netty (netty) Fixed in 4.2.16.Final, 4.1.136.Final
  • Fix · GHSA-q6cq-mhr2-jmr5 io.netty:netty-codec-haproxy (Maven) Fixed in 4.2.16.Final Advisory →
  • Fix · GHSA-q6cq-mhr2-jmr5 io.netty:netty-codec-haproxy (Maven) Fixed in 4.1.136.Final Advisory →

Red Hat 12 advisories

  • RHSA-2026:90321 Released 2026-10-26 · Red Hat rating Critical
    Red Hat OpenShift Dev Spaces 3.31.0 Release.
    • Red Hat OpenShift Dev Spaces 3.31 registry.redhat.io/devspaces/code-rhel9, registry.redhat.io/devspaces/dashboard-rhel9, registry.redhat.io/devspaces/jetbrains-ide-rhel9 +8
  • RHSA-2026:84734 Released 2026-10-19 · Red Hat rating Critical
    RHOAI 3.4.5 - Red Hat OpenShift AI
    • Red Hat OpenShift AI 3.4 registry.redhat.io/rhoai/odh-ai-gateway-payload-processing-rhel9, registry.redhat.io/rhoai/odh-automl-rhel9, registry.redhat.io/rhoai/odh-autorag-rhel9 +47
  • RHSA-2026:69296 Released 2026-09-21 · Red Hat rating Important
    Red Hat Data Grid 8.6.3 security update
    • Red Hat Data Grid 8.6.3
Show 9 more Red Hat advisories
  • RHSA-2026:68333 Released 2026-09-16 · Red Hat rating Important
    Red Hat build of Cryostat security update
    • Cryostat 4 on RHEL 9 cryostat/cryostat-agent-init-rhel9, cryostat/cryostat-grafana-dashboard-rhel9, cryostat/cryostat-openshift-console-plugin-rhel9 +5
  • RHSA-2026:66488 Released 2026-09-10 · Red Hat rating Important
    Red Hat AMQ Broker 7.14.1 release and security update
    • Red Hat AMQ Broker 7.14.1
  • RHSA-2026:65126 Released 2026-09-08 · Red Hat rating Important
    RHOAI 2.25.11 - Red Hat OpenShift AI
    • Red Hat OpenShift AI 2.25 registry.redhat.io/rhoai/odh-built-in-detector-rhel9, registry.redhat.io/rhoai/odh-caikit-tgis-serving-rhel9, registry.redhat.io/rhoai/odh-dashboard-rhel9 +47
  • RHSA-2026:54622 Released 2026-08-13 · Red Hat rating Important
    Red Hat Build of Apache Camel 4.18.3 for Spring Boot release.
    • Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16
  • RHSA-2026:50846 Released 2026-08-05 · Red Hat rating Important
    Red Hat build of Keycloak 26.4.14 Security Update
    • Red Hat build of Keycloak 26.4.14
  • RHSA-2026:50848 Released 2026-08-05 · Red Hat rating Important
    Red Hat build of Keycloak 26.6.5 Security Update
    • Red Hat build of Keycloak 26.6.5
  • RHSA-2026:48118 Released 2026-07-30 · Red Hat rating Important
    Red Hat Build of Apache Camel 4.18.3 for Quarkus 3.33 update is now available (RHBQ 3.33.2.SP3)
    • Red Hat Build of Apache Camel 3.33.2.SP3 io.netty.netty-codec-haproxy-4.1.136.Final-redhat-00001.jar, io.netty.netty-codec-http-4.1.136.Final-redhat-00001.jar, io.netty.netty-codec-http2-4.1.136.Final-redhat-00001.jar +9
  • RHSA-2026:47172 Released 2026-07-30 · Red Hat rating Important
    Red Hat build of Quarkus 3.33.2.SP3 security update
    • Red Hat build of Quarkus 3.33.2.SP3 io.netty.netty-codec-haproxy-4.1.136.Final-redhat-00001.jar, io.netty.netty-codec-http-4.1.136.Final-redhat-00001.jar, io.netty.netty-codec-http2-4.1.136.Final-redhat-00001.jar +3
  • RHSA-2026:47189 Released 2026-07-29 · Red Hat rating Important
    Red Hat build of Quarkus 3.27.4.SP3 security update
    • Red Hat build of Quarkus 3.27.4.SP3 io.netty.netty-codec-haproxy-4.1.136.Final-redhat-00001.jar, io.netty.netty-codec-http-4.1.136.Final-redhat-00001.jar, io.netty.netty-codec-http2-4.1.136.Final-redhat-00001.jar +3

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
OpenShift ServerlessAffectedNo fix yet
Red Hat Build of KeycloakAffectedNo fix yet
Red Hat JBoss Enterprise Application Platform 7AffectedNo fix yet: Fix deferred
Red Hat Single Sign-On 7AffectedNo fix yet: Fix deferred
Red Hat build of Apache Camel - HawtIO 4AffectedNo fix yet
Red Hat build of Apache Camel 4 for Quarkus 3AffectedNo fix yet
Red Hat build of Apicurio Registry 3AffectedNo fix yet
Red Hat build of Debezium 3AffectedNo fix planned: Will not fix
Red Hat build of QuarkusAffectedNo fix yet: Fix deferred
streams for Apache Kafka 3AffectedNo fix yet
Cryostat 4 on RHEL 9Fixed RHSA-2026:68333
Red Hat AMQ Broker 7.14.1Fixed RHSA-2026:66488
Red Hat Build of Apache Camel 3.33.2.SP3Fixed RHSA-2026:48118
Red Hat Data Grid 8.6.3Fixed RHSA-2026:69296
Red Hat OpenShift AI 2.25Fixed RHSA-2026:65126
Red Hat OpenShift AI 3.4Fixed RHSA-2026:84734
Red Hat OpenShift Dev Spaces 3.31Fixed RHSA-2026:90321
Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16Fixed RHSA-2026:54622
Red Hat build of Keycloak 26.4.14Fixed RHSA-2026:50846
Red Hat build of Keycloak 26.6.5Fixed RHSA-2026:50848
Red Hat build of Quarkus 3.27.4.SP3Fixed RHSA-2026:47189
Red Hat build of Quarkus 3.33.2.SP3Fixed RHSA-2026:47172
Not affected: 10 products
  • Cryostat 4 on RHEL 9
  • Red Hat Build of Apache Camel 3.33.2.SP3
  • Red Hat JBoss Enterprise Application Platform Expansion Pack
  • Red Hat OpenShift AI 2.25
  • Red Hat OpenShift AI 3.4
  • Red Hat OpenShift Dev Spaces 3.31
  • Red Hat Satellite 6
  • Red Hat build of Quarkus 3.27.4.SP3
  • Red Hat build of Quarkus 3.33.2.SP3
  • streams for Apache Kafka 2

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55851
  2. 2026-10-03 Alias added: GHSA-q6cq-mhr2-jmr5
  3. 2026-10-09 Fix available: RHSA-2026:48118 · Red Hat
  4. 2026-10-09 Fix available: Red Hat Build of Apache Camel 4.18 for Quarkus 3.33 · Red Hat
  5. 2026-10-10 Fix available: Red Hat Build of Apache Camel 3.33.2.SP3 · Red Hat
  6. 2026-10-20 Fix available: RHSA-2026:84734 · Red Hat
  7. 2026-10-20 Fix available: Red Hat OpenShift AI 3.4 · Red Hat
  8. 2026-10-23 Fix available: RHSA-2026:50846 · Red Hat
  9. 2026-10-23 Fix available: RHSA-2026:50848 · Red Hat
  10. 2026-10-23 Fix available: Red Hat build of Keycloak 26.4.14, Red Hat build of Keycloak 26.6.5 · Red Hat
  11. 2026-10-28 EPSS moved to the 50th–90th percentile
  12. 2026-10-29 Fix available: Red Hat OpenShift Dev Spaces 3.31 · Red Hat
  13. 2026-10-30 Fix available: RHSA-2026:90321 · Red Hat
  14. 2026-11-03 Affected versions changed · Red Hat

References

Patch 2

Advisory 2

Other 3

  • TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
  • TI-2026-30861 Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization CVSS 3.1CRITICAL 9.8
  • TI-2026-30864 Netty: HttpClientCodec response desynchronization CVSS 3.1CRITICAL 9.1
  • TI-2026-30859 Netty: DNS Codec Input Validation Bypass in Netty (Encoder + Decoder) CVSS 3.1CRITICAL 9.1
  • TI-2026-40973 Netty: Missing CertificateID Validation in OCSP Response Allows Replay Attacks CVSS 3.1CRITICAL 9.1
  • TI-2026-40972 Uncontrolled resource consumption in netty CVSS 3.1HIGH 7.5
See all 92 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences