Netty HTTP request smuggling via chunked/Content-Length before 4.2.13.Final
CVE-2026-42581 Published on May 13, 2026

Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization
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.

NVD

Vulnerability Analysis

CVE-2026-42581 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
LOW
Integrity Impact:
LOW
Availability Impact:
NONE

Weakness Type

What is a HTTP Request Smuggling Vulnerability?

When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.

CVE-2026-42581 has been classified to as a HTTP Request Smuggling vulnerability or weakness.


Products Associated with CVE-2026-42581

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-42581 are published in these products:

Netty
 
Canonical Ubuntu Linux
 
Red Hat Cryostat
 
Red Hat Openshift Devspaces
 
Red Hat Quarkus
 
Red Hat Amq Streams
 
Red Hat Serverless
 
Red Hat Amq Broker
 
Red Hat Amq Clients
 
Red Hat Camel Quarkus
 
Red Hat Camel Spring Boot
 
Red Hat Service Registry
 
Red Hat Apicurio Registry
 
Red Hat Debezium
 
Red Hat Build Keycloak
 
Red Hat Optaplanner
 
Red Hat Jboss Data Grid
 
Red Hat Enterprise Linux Ai
 
Red Hat Jboss Fuse
 
Red Hat Jboss Enterprise Application Platform
 
Red Hat Jbosseapxp
 
Red Hat Openshift Ai
 
Red Hat Jboss Enterprise Bpms Platform
 
Red Hat Satellite
 
Red Hat Single Sign On
 
Red Hat Apache Camel Spring Boot
 

Affected Versions

netty: Red Hat Cryostat 4 on RHEL 9: Red Hat Cryostat 4 on RHEL 9: Red Hat Cryostat 4 on RHEL 9: Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16: Red Hat build of Quarkus 3.27.4: Red Hat build of Quarkus 3.33.2: Red Hat OpenShift Dev Spaces 3.28: Red Hat OpenShift Dev Spaces 3.28: Red Hat OpenShift Dev Spaces 3.28: Red Hat OpenShift Dev Spaces 3.29: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat OpenShift Serverless: Red Hat AMQ Broker 7: Red Hat AMQ Clients: Red Hat build of Apache Camel 4 for Quarkus 3: Red Hat build of Apicurio Registry 2: Red Hat build of Apicurio Registry 3: Red Hat build of Debezium 3: Red Hat Build of Keycloak: Red Hat Build of Keycloak: Red Hat Build of Keycloak: Red Hat Build of Keycloak: Red Hat Build of Keycloak: Red Hat build of OptaPlanner 8: Red Hat Data Grid 8: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat Fuse 7: Red Hat JBoss Enterprise Application Platform 7: Red Hat JBoss Enterprise Application Platform 8: Red Hat JBoss Enterprise Application Platform Expansion Pack: Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat OpenShift AI (RHOAI): Red Hat Process Automation 7: Red Hat Satellite 6: Red Hat Satellite 6: Red Hat Single Sign-On 7: Red Hat streams for Apache Kafka 2: Red Hat streams for Apache Kafka 3:

Exploit Probability

EPSS
0.40%
Percentile
31.67%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.