Infinite loop in NanoMQ - CVE-2026-61633
Published: August 19, 2026
Vulnerability identifier: #VU144325
CSH Severity: Low
CVSS v4: 1.8 [CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-61633
CWE-ID: CWE-835
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to an infinite loop in the UNSUBSCRIBE decoder in mqtt_codec.c when processing a malformed UNSUBSCRIBE packet with a zero-length topic name and trailing data. A remote privileged user can send a specially crafted UNSUBSCRIBE packet to cause a denial of service.
User interaction is required because the client must connect to a malicious broker, and affected exploitation targets the client-side MQTTv3.1.1 codec, including bridge mode.
Affected software
NanoMQ
How to mitigate CVE-2026-61633
Install security update from vendor's website.
NanoMQ - update to 0.24.14