CVE-2026-76816

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.

Published 24 Aug 2026, 20:17 UTC Last modified 24 Aug 2026, 20:17 UTC

3.5

CVSS 3.1 LOW base score CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Attack profile

The conditions required to exploit this vulnerability and its potential impact.

Attack vector Adjacent network

Attack complexity Low

Privileges required Low

User interaction None

Scope Unchanged

Confidentiality None

Integrity Low

Availability None

Exploitability2.1

Impact1.4

Affected products

Product applicability statements supplied with the NVD record.

NVD has not published structured affected-product data for this record.

Weakness classification

CWE categories help security teams group the underlying software weakness.

CWECWE-20 CWECWE-626

Source references

External advisories, patches and technical reports attached to this CVE record.

NVD National Vulnerability Database recordnvd.nist.gov 01 Technical reference security-advisories@github.com 02 Technical reference security-advisories@github.com 03 Technical reference security-advisories@github.com