Junglewise Threat Intelligence

CVE-2026-44891: Netty denial of service in StompSubframeDecoder

CVE-2026-44891 · Severity: high · CVSS 7.5 · Published 2026-07-17

Technologies: Netty Project Netty. Vendors: Netty Project.

Executive brief

Netty is a widely used networking framework for building Java-based server and client applications. A vulnerability in its STOMP protocol handler allows an attacker to crash a server by sending a flood of small message headers. This can lead to a complete service outage (Denial of Service) as the server runs out of memory trying to process the malicious data.

Technical details

A vulnerability exists in the io.netty.handler.codec.stomp.StompSubframeDecoder component of Netty. The decoder fails to enforce a limit on the total number of headers or the cumulative size of headers within a single STOMP frame; the existing maxLineLength parameter only restricts individual header lines. An unauthenticated remote attacker can exploit this by sending a large number of short headers that accumulate in memory within the DefaultStompHeadersSubframe object. This eventually triggers a Java Virtual Machine (JVM) OutOfMemoryError (OOME), resulting in a Denial of Service (DoS). The issue is resolved in versions 4.1.136.Final and 4.2.16.Final by enforcing a limit on the number of headers per frame.

Affected products

  • Netty Project Netty Prior to 4.1.136.Final and 4.2.16.Final

Timeline

  • 2026-07-06: patched: Initial fix merged into 4.2 branch
  • 2026-07-08: patched: Fix backported to 4.1 branch
  • 2026-07-17: disclosed: CVE published

References