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

Source: https://junglewise.ai/threats/cve-2026-44891-netty-denial-of-service-in-stompsubframedecoder  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-17. Updated: 2026-07-17  
License: CC BY 4.0 with a link back

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

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.

Vendors: [Maven](https://junglewise.ai/threats/vendors/maven), [Netty Project](https://junglewise.ai/threats/vendors/netty-project).

## Quick answers

**Is CVE-2026-44891 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44891 being exploited in the wild.

**How severe is CVE-2026-44891?** High severity, with a CVSS score of 7.5, published 17 July 2026.

**Which products and versions are affected?** io.netty:netty-codec-stomp (Maven) ECOSYSTEM:introduced=4.2.0.Alpha1,fixed=4.2.16.Final; Netty Project Codec Stomp >= 4.2.0.Alpha1, <= 4.2.15.Final; <= 4.1.135.Final.

**Is there a fix for CVE-2026-44891?** Yes. io.netty:netty-codec-stomp (Maven): upgrade to 4.2.16.Final or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44891 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-44891?** Check whether you run io.netty:netty-codec-stomp (Maven) or Netty Project Codec Stomp at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- io.netty:netty-codec-stomp (Maven): upgrade to 4.2.16.Final or later

  ```sh
  # set io.netty:netty-codec-stomp to 4.2.16.Final in your pom.xml or build.gradle
  ```


## 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

## Identifiers

- CVE-2026-44891
- GHSA-vhch-2wf3-m8rp

## 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

- [https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b](https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b)
- [https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6](https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6)
- [https://github.com/netty/netty/pull/17063](https://github.com/netty/netty/pull/17063)
- [https://github.com/netty/netty/pull/17065](https://github.com/netty/netty/pull/17065)
- [https://github.com/netty/netty/releases/tag/netty-4.1.136.Final](https://github.com/netty/netty/releases/tag/netty-4.1.136.Final)
- [https://github.com/netty/netty/releases/tag/netty-4.2.16.Final](https://github.com/netty/netty/releases/tag/netty-4.2.16.Final)
- [https://github.com/netty/netty/security/advisories/GHSA-vhch-2wf3-m8rp](https://github.com/netty/netty/security/advisories/GHSA-vhch-2wf3-m8rp)

## Related threats

- [Netty STOMP header injection in CONNECT frames](https://junglewise.ai/threats/cve-2026-59920-netty-stomp-header-injection-in-connect-frames)