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Advisory severityMedium5.3Red Hat Linux

Medium [CVE-2026-59898] Protocol version confusion in netty-codec-http (WebSocket)

This medium-severity Red Hat Linux advisory covers CVE-2026-59898 affecting Red Hat build of Quarkus 3.27.4.SP3, Red Hat build of Quarkus 3.33.2.SP3, Cryostat 4.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-59898 Source published Source updated

VulniPulse record published Record updated

CVE-2026-59898
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

Summary

Netty is an asynchronous, event-driven network application framework.

Prior to versions 4.1.136.Final and 4.2.16.Final, ab attacker can force WebSocket upgrade via the lax V07 (or V08) handshaker by sending `Sec-WebSocket-Version: 7` and omitting `Connection: Upgrade` / `Upgrade: websocket` headers, completing a protocol switch that a proxy would not recognize as an Upgrade request and enabling HTTP request smuggling / protocol-confusion attacks.

A flaw was found in netty-codec-http. The WebSocket handshaker in this component fails to properly validate protocol version information during the WebSocket upgrade process.

A remote attacker can exploit this vulnerability by manipulating the WebSocket handshake, leading to a bypass of security checks or the negotiation of unexpected protocol versions. This could potentially enable protocol-level attacks.

Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N). Weakness: CWE-358.

Affected products named by the advisory: Red Hat build of Quarkus 3.27.4.SP3; Red Hat build of Quarkus 3.33.2.SP3; Cryostat 4; OpenShift Serverless; and 19 more.

Is CVE-2026-59898 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-59898 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-59898?

Upgrade to a fixed release named by Red Hat:

  • 4.1.136
  • 4.2.16
  • io.netty/netty-codec-http:4.1.136.Final-redhat-00001
  • RHSA-2026:47189
  • RHSA-2026:47172

Confirm against the vendor advisory before you patch.

Affected versions
  • < 4.1.136.Final
  • < 4.2.16.Final

Official advisory · high-confidence parse· fetched 3 days ago·verify at source

Fixed versions
  • 4.1.136
  • 4.2.16
  • io.netty/netty-codec-http:4.1.136.Final-redhat-00001
  • RHSA-2026:47189
  • RHSA-2026:47172

Official advisory · high-confidence parse· fetched 3 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Official advisory · high-confidence parse· fetched 3 days ago·verify at source

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