Input validation error in Netty - CVE-2026-59898

Vulnerability identifier: #VU137559

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-59898

CWE-ID: CWE-20

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to perform HTTP request smuggling and protocol-confusion attacks.

The vulnerability exists due to improper input validation in the WebSockets V07/V08 handshaker when handling WebSocket upgrade requests. A remote attacker can send a specially crafted request with Sec-WebSocket-Version: 7 while omitting Connection: Upgrade and Upgrade: websocket headers to perform HTTP request smuggling and protocol-confusion attacks.

The issue affects protocol switching behavior in cases where an intermediary proxy would not recognize the request as a WebSocket upgrade.

Netty
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Real Time 15
Development Tools Module
SUSE Package Hub 15
netty-tcnative-debugsource
netty-tcnative
netty
netty-javadoc

Install security update from vendor's website.

Netty - addressed in versions 4.1.136, 4.2.16
netty-tcnative-debugsource - update to 2.0.80-150200.3.48.1
netty-tcnative - update to 2.0.80-150200.3.48.1
netty - update to 4.1.136-150200.4.53.1
netty-javadoc - update to 4.1.136-150200.4.53.1

• https://github.com/netty/netty/security/advisories/GHSA-4mp9-239f-g9hg

• Multiple vulnerabilities in Netty
• SUSE update for netty, netty-tcnative