CVE-2026-76816Netty: MQTT Topic Name and Client ID Validation Bypass
Updated under an hour ago ()
Does this affect you?
It affects netty. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
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
- 3.5 LOW (v3.1, CNA)CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
- Weakness (CWE)
- CWE-20, CWE-626
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Aug 25, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
netty netty netty:netty (from the name) | from 4.2.0.Final, < 4.1.137.Final; before 4.1.137.Final | CNA record |
References
- https://github.com/netty/netty/security/advisories/GHSA-43fm-7cxg-hf3jx-refsource-confirm
- https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7x-refsource-misc
- https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.