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Fencer Intel
medium 5.7

CVE-2026-59921 json

Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder

published 3mo ago modified 2mo ago also EUVD-2026-50089 , GHSA-gcjf-9mgh-3p7g

cvss
5.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
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, HttpPostRequestEncoder constructs multipart HTTP request bodies by directly concatenating user-supplied filenames and field names into Content-Disposition MIME headers without validating or sanitizing CRLF characters (\r\n). Since MIME headers are delimited by CRLF, an attacker who controls the filename can inject arbitrary MIME headers into the multipart body part. The root cause is that neither the encoder nor the FileUpload implementations' setFilename() methods, which only check for null, neutralize CRLF characters before the filename is embedded into the header. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

Patch / fix

  • maven io.netty:netty-codec-http 4.1.136.Final, 4.2.16.Final
  • io.netty netty-codec-http 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

Is CVE-2026-59921 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-59921 updated cvss 5.7

io.netty/netty-codec-http: Netty: CRLF Injection via Multipart Filename in Netty HttpPostRequestEncoder

  • Red Hat Cryostat 4 netty-codec-http 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-http 4.1.132.Final-redhat-00001 Red Hat AMQ Clients netty-codec-http 4.1.132.Final-redhat-00001 Red Hat build of Apache Camel - HawtIO 4 netty-codec-http 4.1.132.Final-redhat-00001 Red Hat build of Apache Camel 4 for Quarkus 3 netty-codec-http 4.1.132.Final-redhat-00001
    +16 more products
    Red Hat build of Apache Camel for Spring Boot 4 netty-codec-http 4.1.132.Final-redhat-00001 Red Hat build of Apicurio Registry 3 netty-codec-http 4.1.132.Final-redhat-00001 Red Hat build of Debezium 3 netty-codec-http 4.1.132.Final-redhat-00001 Red Hat Build of Keycloak rhbk-keycloak-rhel9, rhbk-rhel9-operator, rhbk-openshift-rhel9, rhbk-keycloak-rhel9-operator, netty-codec-http 4.1.132.Final-redhat-00001 Red Hat build of Quarkus netty-codec-http 4.1.132.Final-redhat-00001 Red Hat Data Grid 8 netty-codec-http 4.1.132.Final-redhat-00001 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 Red Hat JBoss Enterprise Application Platform 7 eap74-els-openjdk8-openshift-rhel8, eap74-els-openjdk11-openshift-rhel8, eap74-els-openjdk17-openshift-rhel8, netty-codec-http 4.1.132.Final-redhat-00001, jboss-eap-7-eap74-els-openjdk8-openshift-rhel8, jboss-eap-7-eap74-els-openjdk17-openshift-rhel8 Red Hat JBoss Enterprise Application Platform 8 netty-codec-http 4.1.132.Final-redhat-00001 Red Hat JBoss Enterprise Application Platform Expansion Pack netty-codec-http 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 Red Hat Satellite 6 candlepin, candlepin-selinux Red Hat Single Sign-On 7 netty-codec-http 4.1.132.Final-redhat-00001 Red Hat streams for Apache Kafka 2 netty-codec-http 4.1.132.Final-redhat-00001 Red Hat streams for Apache Kafka 3 netty-codec-http 4.1.132.Final-redhat-00001
    affected: workaround, no fix available “Fix deferred”
  • Red Hat build of Quarkus 3.27.4.SP3 netty-codec-http 4.1.136.Final-redhat-00001
    fixed: vendor fix RHSA-2026:47189
  • Red Hat build of Quarkus 3.33.2.SP3 netty-codec-http 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
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/netty/netty/security/advisories/GHSA-gcjf-9mgh-3p7g referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.7 CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
GitHub 3.1 5.7 CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
maven io.netty:netty-codec-http
>=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-93 Improper Neutralization of CRLF Sequences

References

Sources

Fencer Intel 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.