Vulnerability Description
Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.137.Final and 4.2.17.Final, MqttEncoder does not validate client identifiers, will topics, usernames, and PUBLISH topic names before encoding, allowing prohibited null bytes in MQTT UTF-8 string fields and potentially causing routing, access-control, or identity mismatches in downstream brokers. The vulnerability is exploitable when an application uses Netty's MQTT encoder to construct messages from user-controlled input. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.
CVSS Score
LOW
Related Weaknesses (CWE)
References
- https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7
- https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961
- https://github.com/netty/netty/security/advisories/GHSA-43fm-7cxg-hf3j
FAQ
What is CVE-2026-76816?
CVE-2026-76816 is a vulnerability with a CVSS score of 3.5 (LOW). Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.137.Final and 4.2.17.Final, MqttEncoder does not validate client identifiers, will topics, usernames, and PU...
How severe is CVE-2026-76816?
CVE-2026-76816 has been rated LOW with a CVSS base score of 3.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-76816?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.