---
id: CVE-2026-61633
title: NanoMQ is an MQTT broker
summary: >-
  NanoMQ is an MQTT broker. Prior to 0.24.14, the NanoMQ client function
  nni_mqtt_msg_decode_unsubscribe() in nng/src/supplemental/mqtt/mqtt_codec.c
  does not handle a failed read_uint16() while counting topics in a malformed
  UNSUBSCRIBE pa…
severity: low
cvss: 2
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L'
cwe:
  - CWE-835
vendor: nanomq
product: nanomq
affected:
  - nanomq < 0.24.14
published: '2026-09-18'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T18:17:09.433'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-61633'
references:
  - url: >-
      https://github.com/nanomq/NanoNNG/commit/fa8d859bb39841e46cfc6cce280d242bd782ad3d
    label: security-advisories@github.com
  - url: 'https://github.com/nanomq/NanoNNG/pull/1518'
    label: security-advisories@github.com
  - url: 'https://github.com/nanomq/nanomq/releases/tag/0.24.14'
    label: security-advisories@github.com
  - url: 'https://github.com/nanomq/nanomq/security/advisories/GHSA-m7mp-rr3v-hmhr'
    label: security-advisories@github.com
  - url: 'https://github.com/nanomq/nanomq/security/advisories/GHSA-m7mp-rr3v-hmhr'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-18T17:26:25.126842Z'
ingestedAt: '2026-09-18T16:45:41.410Z'
epss: 0.00253
epssPercentile: 0.17153
---

## Overview

NanoMQ is an MQTT broker. Prior to 0.24.14, the NanoMQ client function nni_mqtt_msg_decode_unsubscribe() in nng/src/supplemental/mqtt/mqtt_codec.c does not handle a failed read_uint16() while counting topics in a malformed UNSUBSCRIBE packet. A zero-length topic followed by trailing data can leave buf.curpos unchanged while topic_count continues to increase, allowing a malicious MQTT broker to hang a connecting MQTT 3.1.1 client, consume CPU and memory, and repeatedly deny service when automatic reconnection is enabled. The broker-side nmq_unsubinfo_decode path is not affected. This issue is fixed in version 0.24.14.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.