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Fencer Vulns
medium 5.3

CVE-2026-59900 json

Netty codec-http2: Lack of Host Header Deduplication in HTTP/2→HTTP/1.x Translation Leads to Request Routing Bypass

published 2026-07-22 3 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-50442 , GHSA-c69g-56f8-xwqj

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, Netty's HTTP/2-to-HTTP/1.x translation layer (`Http2StreamFrameToHttpObjectCodec` and `InboundHttp2ToHttpAdapter`) fails to deduplicate or validate `Host` headers when an HTTP/2 client supplies both the `:authority` pseudo-header and a literal `host` header in a single HEADERS frame. The translator maps `:authority` to `Host` and separately copies the literal `host` header, producing an `HttpRequest` object containing two `Host` headers with attacker-controlled differing values. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Patch / fix

  • maven io.netty:netty-codec-http2 4.1.136.Final, 4.2.16.Final
  • io.netty netty-codec-http2 4.1.136.Final, 4.2.16.Final
  • netty netty 4.1.136.Final, 4.2.16.Final
  • 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-2026-59900 updated cvss 6.5

io.netty/netty-codec-http2: Netty: Improper header neutralization in netty-codec-http2

  • Red Hat Cryostat 4 netty-codec-http2 4.1.132.Final-redhat-00001 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 4.1.132.Final-redhat-00001 Red Hat build of Apache Camel - HawtIO 4 netty-codec-http2 4.1.132.Final-redhat-00001 Red Hat build of Apache Camel 4 for Quarkus 3 netty-codec-http2 4.1.132.Final-redhat-00001 Red Hat build of Apache Camel for Spring Boot 4 netty-codec-http2 4.1.132.Final-redhat-00001
    +2 more products
    Red Hat build of Apicurio Registry 3 netty-codec-http2 4.1.132.Final-redhat-00001 Red Hat build of Debezium 3 netty-codec-http2 4.1.132.Final-redhat-00001
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Build of Keycloak rhbk-keycloak-rhel9, rhbk-rhel9-operator, rhbk-openshift-rhel9, rhbk-keycloak-rhel9-operator, netty-codec-http2 4.1.132.Final-redhat-00001
    affected: workaround, no fix available, no fix planned “Out of support scope”
  • Red Hat build of Quarkus netty-codec-http2 4.1.132.Final-redhat-00001 Red Hat Data Grid 8 netty-codec-http2 4.1.132.Final-redhat-00001
    affected: workaround, no fix planned “Out of support scope”
  • 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 “Fix deferred”
  • Red Hat JBoss Enterprise Application Platform 7 eap74-els-openjdk8-openshift-rhel8, eap74-els-openjdk11-openshift-rhel8, eap74-els-openjdk17-openshift-rhel8, netty-codec-http2 4.1.132.Final-redhat-00001, jboss-eap-7-eap74-els-openjdk8-openshift-rhel8, jboss-eap-7-eap74-els-openjdk17-openshift-rhel8
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat JBoss Enterprise Application Platform Expansion Pack netty-codec-http2 4.1.132.Final-redhat-00001 Red Hat OpenShift AI (RHOAI) rhoai/odh-modelmesh-rhel9, rhoai/odh-spark-operator-rhel9, rhoai/odh-trustyai-service-rhel9, rhoai/odh-th06-cpu-torch210-py312-rhel9, rhoai/odh-th06-cpu-torch291-py312-rhel9, rhoai/odh-th06-rocm64-torch291-py312-rhel9, +2 more Red Hat OpenShift Dev Spaces devspaces/server-rhel9, devspaces/openvsx-rhel9, devspaces/jetbrains-ide-rhel9, devspaces/pluginregistry-rhel9, devspaces/multicluster-redirector-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Single Sign-On 7 netty-codec-http2 4.1.132.Final-redhat-00001 Red Hat streams for Apache Kafka 2 netty-codec-http2 4.1.132.Final-redhat-00001
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat streams for Apache Kafka 3 netty-codec-http2 4.1.132.Final-redhat-00001
    affected: workaround, no fix available “Fix deferred”
show 3 more
  • Red Hat build of Quarkus 3.27.4.SP3 netty-codec-http2 4.1.136.Final-redhat-00001
    fixed: vendor fix RHSA-2026:47189
  • Red Hat build of Quarkus 3.33.2.SP3 netty-codec-http2 4.1.136.Final-redhat-00001
    fixed: vendor fix RHSA-2026:47172
  • 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
    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
3 mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven io.netty:netty-codec-http2
>=4.2.0.Final, <4.2.16.Final
<4.1.136.Final
4.2.16.Final
4.1.136.Final

Affected products

  • netty netty

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

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.