| Name | CVE-2026-76816 |
| 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| netty (PTS) | bullseye | 1:4.1.48-4+deb11u2 | vulnerable |
| bullseye (security) | 1:4.1.48-4+deb11u3 | vulnerable | |
| bookworm, bookworm (security) | 1:4.1.48-7+deb12u2 | vulnerable | |
| trixie (security), trixie | 1:4.1.48-10+deb13u1 | vulnerable | |
| forky, sid | 1:4.1.48-16 | vulnerable |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| netty | source | (unstable) | (unfixed) |
https://github.com/netty/netty/security/advisories/GHSA-43fm-7cxg-hf3j
Fixed by: https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7 (netty-4.2.17.Final)
Fixed by: https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961 (netty-4.1.137.Final)