CVE-2026-59920: Netty STOMP header injection in CONNECT frames

CVE-2026-59920 · Severity: medium · CVSS 6.5 · Published 2026-07-29

Netty is a widely used networking framework for Java applications. A vulnerability in its STOMP protocol component allows attackers to inject malicious headers into connection requests. This could enable an attacker to bypass authentication, escalate their privileges, or hijack connection parameters, depending on how the backend message broker is configured.

Vendors: Maven, Netty Project.

Quick answers

Is CVE-2026-59920 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-59920 being exploited in the wild.
How severe is CVE-2026-59920?
Medium severity, with a CVSS score of 6.5, published 29 July 2026.
Which products and versions are affected?
io.netty:netty-codec-stomp (Maven) ECOSYSTEM:introduced=4.2.0.Final,fixed=4.2.16.Final; Netty Project Netty-Codec-Stomp < 4.1.136.Final, >= 4.2.0.Final, < 4.2.16.Final.
Is there a fix for CVE-2026-59920?
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-2026-59920 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-59920?
Check whether you run io.netty:netty-codec-stomp (Maven) or Netty Project Netty-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
    # set io.netty:netty-codec-stomp to 4.2.16.Final in your pom.xml or build.gradle

Technical details

The vulnerability exists in the 'StompSubframeEncoder' component of Netty's STOMP codec. While the STOMP 1.2 specification mandates that CONNECT and CONNECTED frames should not use standard header escaping for backward compatibility, Netty's implementation fails to perform validation to reject raw newline (\n) characters. An attacker who can control a header value (such as a login or passcode) can inject a raw newline followed by additional header fields. When the downstream broker parses the frame, it interprets these injected lines as legitimate headers. This can lead to authentication bypass or privilege escalation if the broker relies on specific headers for security decisions. The issue is resolved in versions 4.1.136.Final and 4.2.16.Final by adding validation to reject newlines in these frames.

Affected products

  • Netty netty-codec-stomp < 4.1.136.Final, >= 4.2.0.Final, < 4.2.16.Final

Identifiers

  • CVE-2026-59920
  • GHSA-3g8r-4pfx-jmfh

Timeline

  • 2026-07-14: advisory: GitHub Security Advisory published by maintainers
  • 2026-07-29: disclosed: NVD publication date

References

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