CVE-2026-76816lowCWE-20CWE-626

CVE-2026-76816: low-severity vulnerability in netty

Netty: MQTT Topic Name and Client ID Validation Bypass

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8Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 3.5epss 0.2%
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:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Affected products
netty · netty
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