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.
Attack Parameters
Attack Vector
Adjacent
Requires local network access
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 3
https://github.com/netty/netty/commit/1b5abc6443b63726c72cdd285af2feb7ddbb8ff7
security-advisories@github.com
https://github.com/netty/netty/commit/9e0519239108a69b7e9bbc5e9182ee139a0d7961
security-advisories@github.com
https://github.com/netty/netty/security/advisories/GHSA-43fm-7cxg-hf3j
security-advisories@github.com