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Fencer Vulns
medium 5.3

CVE-2026-50020 json

Netty's HttpObjectDecoder skips arbitrary initial control characters when only initial CRLF characters are permitted

published 2026-06-12 4 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-36468 , GHSA-hvcg-qmg6-jm4c

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 14%
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, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore empty CRLF lines preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Patch / fix

  • maven io.netty:netty-codec-http 4.1.135.Final, 4.2.15.Final
  • io.netty netty-codec-http 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-2026-50020 updated cvss 5.3

netty-codec-http: Netty: Data manipulation via request-boundary confusion in HttpObjectDecoder

  • Red Hat Cryostat 4 netty-codec-http 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-http Red Hat AMQ Clients netty-codec-http Red Hat build of Apache Camel - HawtIO 4 netty-codec-http Red Hat build of Apache Camel 4 for Quarkus 3 netty-codec-http
    +14 more products
    Red Hat build of Apache Camel for Spring Boot 4 netty-codec-http Red Hat build of Apicurio Registry 3 netty-codec-http Red Hat build of Debezium 3 netty-codec-http Red Hat Build of Keycloak netty-codec-http, rhbk-rhel9-operator, rhbk/keycloak-rhel9, rhbk-openshift-rhel9, rhbk/keycloak-rhel9-operator Red Hat Data Grid 8 netty-codec-http Red Hat Fuse 7 netty-codec-http Red Hat JBoss Enterprise Application Platform 7 netty-codec-http Red Hat JBoss Enterprise Application Platform 8 netty-codec-http Red Hat JBoss Enterprise Application Platform Expansion Pack netty-codec-http 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/server-rhel9, devspaces/openvsx-rhel9, devspaces/jetbrains-ide-rhel9, devspaces/pluginregistry-rhel9, devspaces/multicluster-redirector-rhel9 Red Hat Single Sign-On 7 netty-codec-http Red Hat streams for Apache Kafka 2 netty-codec-http Red Hat streams for Apache Kafka 3 netty-codec-http
    affected: workaround, no fix available “Fix deferred”
  • Red Hat build of Quarkus 3.27.4.SP1 netty-codec-http 4.1.135.Final-redhat-00001
    fixed: vendor fix RHSA-2026:26018
  • Red Hat build of Quarkus 3.33.2.SP1 netty-codec-http 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 Satellite 6 candlepin, candlepin-selinux
    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
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c referenced PoC, tagged "exploit" by a source, unverified

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:L/A:N
GitHub 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-http
>=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-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.