Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 26 fixed, 12 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA, GitHub and Red Hat.
Summary
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- 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
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| netty | netty | 4.2.0.Alpha1 to before 4.2.13.Final; before 4.1.133.Final | 4.2.13.Final, 4.1.133.Final | Patch available | CNA |
| — | io.netty:netty-codec-http (Maven) | 4.2.0.Alpha1 to before 4.2.13.Final | 4.2.13.Final | Patch available | GHSA-xxqh-mfjm-7mv9 |
| — | io.netty:netty-codec-http (Maven) | before 4.1.133.Final | 4.1.133.Final | Patch available | GHSA-xxqh-mfjm-7mv9 |
- netty Vendornetty Affected 4.2.0.Alpha1 to before 4.2.13.Final; before 4.1.133.Final Fixed in 4.2.13.Final, 4.1.133.Final Patch available CNA
- io.netty:netty-codec-http (Maven) Vendor— Affected 4.2.0.Alpha1 to before 4.2.13.Final Fixed in 4.2.13.Final Patch available GHSA-xxqh-mfjm-7mv9
- io.netty:netty-codec-http (Maven) Vendor— Affected before 4.1.133.Final Fixed in 4.1.133.Final Patch available GHSA-xxqh-mfjm-7mv9
Remediation
- Fix · CNA netty (netty) Fixed in 4.2.13.Final, 4.1.133.Final
- Fix · GHSA-xxqh-mfjm-7mv9 io.netty:netty-codec-http (Maven) Fixed in 4.2.13.Final Advisory →
- Fix · GHSA-xxqh-mfjm-7mv9 io.netty:netty-codec-http (Maven) Fixed in 4.1.133.Final Advisory →
Red Hat 27 advisories
- RHSA-2026:84734 Released 2026-10-19 · Red Hat rating CriticalRHOAI 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-2026:76128 Released 2026-10-06 · Red Hat rating ImportantRed Hat Single Sign-On 7.6.13 security update on RHEL 7
- Red Hat Single Sign-On 7.6 for RHEL 7 Server rh-sso7-keycloak-18.0.20-1.redhat_00001.1.el7sso, rh-sso7-keycloak-server-18.0.20-1.redhat_00001.1.el7sso
- RHSA-2026:76130 Released 2026-10-06 · Red Hat rating ImportantRed Hat Single Sign-On 7.6.13 security update on RHEL 9
- Red Hat Single Sign-On 7.6 for RHEL 9 rh-sso7-keycloak-18.0.20-1.redhat_00001.1.el9sso, rh-sso7-keycloak-server-18.0.20-1.redhat_00001.1.el9sso
Show 24 more Red Hat advisories
- RHSA-2026:76129 Released 2026-10-06 · Red Hat rating ImportantRed Hat Single Sign-On 7.6.13 security update on RHEL 8
- Red Hat Single Sign-On 7.6 for RHEL 8 rh-sso7-keycloak-18.0.20-1.redhat_00001.1.el8sso, rh-sso7-keycloak-server-18.0.20-1.redhat_00001.1.el8sso
- RHSA-2026:76134 Released 2026-10-05 · Red Hat rating ImportantRed Hat Single Sign-On 7.6.13 for OpenShift image security update
- Middleware Containers for OpenShift rh-sso-7/sso76-openshift-rhel8
- RHSA-2026:76132 Released 2026-10-05 · Red Hat rating ImportantRed Hat Single Sign-On 7.6.13 security update
- Red Hat Single Sign-On 7.6.13
- RHSA-2026:73976 Released 2026-09-30 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 7.1.16 security update
- Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 Server eap7-hibernate-5.1.17-5.Final_redhat_00006.1.ep7.el7, eap7-hibernate-core-5.1.17-5.Final_redhat_00006.1.ep7.el7, eap7-hibernate-entitymanager-5.1.17-5.Final_redhat_00006.1.ep7.el7 +7
- RHSA-2026:73644 Released 2026-09-30 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 7.3.19 Update
- Red Hat JBoss Enterprise Application Platform 7.3 EUS for RHEL 7 Server eap7-hibernate-5.3.39-1.Final_redhat_00001.1.el7eap, eap7-hibernate-core-5.3.39-1.Final_redhat_00001.1.el7eap, eap7-hibernate-entitymanager-5.3.39-1.Final_redhat_00001.1.el7eap +31
- RHSA-2026:69459 Released 2026-09-21 · Red Hat rating ImportantAMQ Clients 2026.Q3
- AMQ Clients 2026.Q3
- RHSA-2026:66545 Released 2026-09-10 · Red Hat rating ImportantRed Hat AMQ Broker 7.13.6 release and security update
- Red Hat AMQ Broker 7.13.6
- RHSA-2026:66488 Released 2026-09-10 · Red Hat rating ImportantRed 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 ImportantRHOAI 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-2026:54435 Released 2026-08-12 · Red Hat rating ImportantStreams for Apache Kafka 3.2.1 release and security update
- Streams for Apache Kafka 3.2.1
- RHSA-2026:53806 Released 2026-08-11 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 7.4.25 security update
- Red Hat JBoss Enterprise Application Platform 7.4.25
- RHSA-2026:53646 Released 2026-08-11 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 7.4.25 Security update
- Red Hat JBoss EAP 7.4 ELS for RHEL 9 eap7-activemq-artemis-2.16.0-22.redhat_00057.1.el9eap, eap7-activemq-artemis-cli-2.16.0-22.redhat_00057.1.el9eap, eap7-activemq-artemis-commons-2.16.0-22.redhat_00057.1.el9eap +47
- RHSA-2026:53645 Released 2026-08-11 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 7.4.25 Security update
- Red Hat JBoss EAP 7.4 ELS for RHEL 8 eap7-activemq-artemis-2.16.0-22.redhat_00057.1.el8eap, eap7-activemq-artemis-cli-2.16.0-22.redhat_00057.1.el8eap, eap7-activemq-artemis-commons-2.16.0-22.redhat_00057.1.el8eap +47
- RHSA-2026:53644 Released 2026-08-11 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 7.4.25 security pdate
- Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server eap7-activemq-artemis-2.16.0-22.redhat_00057.1.el7eap, eap7-activemq-artemis-cli-2.16.0-22.redhat_00057.1.el7eap, eap7-activemq-artemis-commons-2.16.0-22.redhat_00057.1.el7eap +47
- RHSA-2026:49700 Released 2026-08-03 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 8.1.7 security update
- Red Hat JBoss EAP 8.1 for RHEL 10 eap8-eap-product-conf-parent-801.7.1-1.GA_redhat_00001.1.el10eap, eap8-eap-product-conf-wildfly-ee-feature-pack-801.7.1-1.GA_redhat_00001.1.el10eap, eap8-netty-4.1.135-1.Final_redhat_00001.1.el10eap +17
- Red Hat JBoss EAP 8.1 for RHEL 8 eap8-eap-product-conf-parent-801.7.1-1.GA_redhat_00001.1.el8eap, eap8-eap-product-conf-wildfly-ee-feature-pack-801.7.1-1.GA_redhat_00001.1.el8eap, eap8-jose4j-0.9.6-2.redhat_00002.1.el8eap +19
- Red Hat JBoss EAP 8.1 for RHEL 9 eap8-eap-product-conf-parent-801.7.1-1.GA_redhat_00001.1.el9eap, eap8-eap-product-conf-wildfly-ee-feature-pack-801.7.1-1.GA_redhat_00001.1.el9eap, eap8-jose4j-0.9.6-2.redhat_00002.1.el9eap +19
- RHSA-2026:49701 Released 2026-08-03 · Red Hat rating ImportantRed Hat JBoss Enterprise Application Platform 8.1.7 security update
- Red Hat JBoss Enterprise Application Platform 8.1.7.GA io.netty.netty-codec-dns-4.1.135.Final-redhat-00001.jar, io.netty.netty-codec-http-4.1.135.Final-redhat-00001.jar, io.netty.netty-handler-4.1.135.Final-redhat-00001.jar +2
- RHSA-2026:42644 Released 2026-07-21 · Red Hat rating ImportantRHOAI 2.25.9 - Red Hat OpenShift AI
- Red Hat OpenShift AI 2.25 registry.redhat.io/rhoai/odh-caikit-tgis-serving-rhel9, registry.redhat.io/rhoai/odh-feature-server-rhel9, registry.redhat.io/rhoai/odh-kserve-storage-initializer-rhel9 +36
- RHSA-2026:37390 Released 2026-07-09 · Red Hat rating ImportantRed Hat Build of Apache Camel 4.18.1.P1 for Spring Boot release.
- Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16
- RHSA-2026:36820 Released 2026-07-08 · Red Hat rating ImportantRed Hat OpenShift Dev Spaces 3.29.0 Release.
- Red Hat OpenShift Dev Spaces 3.29 registry.redhat.io/devspaces/code-rhel9, registry.redhat.io/devspaces/dashboard-rhel9, registry.redhat.io/devspaces/multicluster-redirector-rhel9 +6
- RHSA-2026:30049 Released 2026-06-25 · Red Hat rating ImportantRed Hat build of Keycloak 26.4.13 Security Update
- Red Hat build of Keycloak 26.4.13
- RHSA-2026:28010 Released 2026-06-22 · Red Hat rating ImportantRed Hat build of Cryostat security update
- Cryostat 4 on RHEL 9 cryostat/cryostat-openshift-console-plugin-rhel9, cryostat/cryostat-reports-rhel9, cryostat/cryostat-rhel9 +3
- RHSA-2026:25123 Released 2026-06-10 · Red Hat rating ImportantRed Hat OpenShift Dev Spaces 3.28.2 Release.
- Red Hat OpenShift Dev Spaces 3.28 registry.redhat.io/devspaces/dashboard-rhel9, registry.redhat.io/devspaces/openvsx-rhel9, registry.redhat.io/devspaces/pluginregistry-rhel9 +1
- RHSA-2026:24502 Released 2026-06-10 · Red Hat rating ImportantRed Hat build of Quarkus 3.33.2 release and security update
- Red Hat build of Quarkus 3.33.2.redhat io.netty.netty-codec-dns-4.1.133.Final-redhat-00002.jar, io.netty.netty-codec-http-4.1.133.Final-redhat-00002.jar, io.netty.netty-handler-proxy-4.1.133.Final-redhat-00002.jar
- RHSA-2026:23808 Released 2026-06-10 · Red Hat rating ImportantRed Hat build of Quarkus 3.27.4 release and security update
- Red Hat build of Quarkus 3.27.4.redhat io.netty.netty-codec-dns-4.1.133.Final-redhat-00002.jar, io.netty.netty-codec-http-4.1.133.Final-redhat-00002.jar, io.netty.netty-codec-http2-4.1.133.Final-redhat-00002.jar +1
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| OpenShift Serverless | Affected | No fix yet |
| Red Hat Build of Keycloak | Affected | No fix yet |
| Red Hat Data Grid 8 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix planned: Will not fix |
| Red Hat Fuse 7 | Affected | No fix planned: Will not fix |
| Red Hat JBoss Enterprise Application Platform Expansion Pack | Affected | No fix planned: Will not fix |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
| Red Hat Process Automation 7 | Affected | No fix planned: Will not fix |
| Red Hat build of Apicurio Registry 2 | Affected | No fix planned: Will not fix |
| Red Hat build of Apicurio Registry 3 | Affected | No fix yet |
| Red Hat build of Debezium 3 | Affected | No fix planned: Will not fix |
| Red Hat build of OptaPlanner 8 | Affected | No fix planned: Out of support scope |
| AMQ Clients 2026.Q3 | Fixed | RHSA-2026:69459 |
| Cryostat 4 on RHEL 9 | Fixed | RHSA-2026:28010 |
| Middleware Containers for OpenShift | Fixed | RHSA-2026:76134 |
| Red Hat AMQ Broker 7.13.6 | Fixed | RHSA-2026:66545 |
| Red Hat AMQ Broker 7.14.1 | Fixed | RHSA-2026:66488 |
| Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server | Fixed | RHSA-2026:53644 |
| Red Hat JBoss EAP 8.1 for RHEL 10 | Fixed | RHSA-2026:49700 |
| Red Hat JBoss EAP 8.1 for RHEL 8 | Fixed | RHSA-2026:49700 |
| Red Hat JBoss EAP 8.1 for RHEL 9 | Fixed | RHSA-2026:49700 |
| Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 Server | Fixed | RHSA-2026:73976 |
| Red Hat JBoss Enterprise Application Platform 7.3 EUS for RHEL 7 Server | Fixed | RHSA-2026:73644 |
| Red Hat JBoss Enterprise Application Platform 7.4.25 | Fixed | RHSA-2026:53806 |
| Red Hat JBoss Enterprise Application Platform 8.1.7.GA | Fixed | RHSA-2026:49701 |
| Red Hat OpenShift AI 2.25 | Fixed | RHSA-2026:42644, RHSA-2026:65126 |
| Red Hat OpenShift AI 3.4 | Fixed | RHSA-2026:84734 |
| Red Hat OpenShift Dev Spaces 3.28 | Fixed | RHSA-2026:25123 |
| Red Hat OpenShift Dev Spaces 3.29 | Fixed | RHSA-2026:36820 |
| Red Hat Single Sign-On 7.6 for RHEL 7 Server | Fixed | RHSA-2026:76128 |
| Red Hat Single Sign-On 7.6 for RHEL 8 | Fixed | RHSA-2026:76129 |
| Red Hat Single Sign-On 7.6 for RHEL 9 | Fixed | RHSA-2026:76130 |
| Red Hat Single Sign-On 7.6.13 | Fixed | RHSA-2026:76132 |
| Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16 | Fixed | RHSA-2026:37390 |
| Red Hat build of Keycloak 26.4.13 | Fixed | RHSA-2026:30049 |
| Red Hat build of Quarkus 3.27.4.redhat | Fixed | RHSA-2026:23808 |
| Red Hat build of Quarkus 3.33.2.redhat | Fixed | RHSA-2026:24502 |
| Streams for Apache Kafka 3.2.1 | Fixed | RHSA-2026:54435 |
Not affected: 13 products
- Cryostat 4 on RHEL 9
- Red Hat Build of Keycloak
- Red Hat JBoss Enterprise Application Platform 8.1.7.GA
- Red Hat OpenShift AI (RHOAI)
- Red Hat OpenShift AI 2.25
- Red Hat OpenShift AI 3.4
- Red Hat OpenShift Dev Spaces 3.28
- Red Hat OpenShift Dev Spaces 3.29
- Red Hat Satellite 6
- Red Hat build of Apache Camel 4 for Quarkus 3
- Red Hat build of Quarkus 3.27.4.redhat
- Red Hat build of Quarkus 3.33.2.redhat
- streams for Apache Kafka 2
Timeline
- 2026-10-02 Threatist record created from CVE-2026-42581
- 2026-10-03 Alias added: GHSA-xxqh-mfjm-7mv9
- 2026-10-06 Fix available: RHSA-2026:76134 · Red Hat
- 2026-10-06 Fix available: RHSA-2026:76132 · Red Hat
- 2026-10-06 Fix available: RHSA-2026:76129 · Red Hat
- 2026-10-06 Fix available: RHSA-2026:76130 · Red Hat
- 2026-10-06 Fix available: Middleware Containers for OpenShift, Red Hat Single Sign-On 7.6 for RHEL 8, Red Hat Single Sign-On 7.6 for RHEL 9 +1 · Red Hat
- 2026-10-07 Fix available: RHSA-2026:76128 · Red Hat
- 2026-10-07 Fix available: Red Hat Single Sign-On 7.6 for RHEL 7 Server · Red Hat
- 2026-10-20 Fix available: RHSA-2026:84734 · Red Hat
- 2026-10-20 Fix available: Red Hat OpenShift AI 3.4, Red Hat build of Quarkus 3.27.4.redhat, Red Hat build of Quarkus 3.33.2.redhat · Red Hat
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-23 Fix available: RHSA-2026:30049 · Red Hat
- 2026-10-23 Fix available: Red Hat build of Keycloak 26.4.13 · Red Hat
- 2026-10-25 EPSS moved to the below the 50th percentile
- 2026-10-27 EPSS moved to the 50th–90th percentile
- 2026-11-01 Affected versions changed · Red Hat
- 2026-11-06 Fix available: RHSA-2026:42644 · Red Hat
References
More Netty vulnerabilities
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- 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
- TI-2026-40298 Netty SPDY SETTINGS frame count materializes unbounded settings map CVSS 3.1HIGH 7.5
Sources
- CVE-2026-42581 · CVE Program
- CVE-2026-42581 · NVD
- FIRST EPSS
- GHSA-xxqh-mfjm-7mv9 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-42581 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences