---
id: CVE-2026-73863
title: NanoMQ is an MQTT broker
summary: >-
  NanoMQ is an MQTT broker. Prior to 0.24.14, NanoMQ's broker-side MQTT v5
  nmq_subinfo_decode() function in nng/src/sp/protocol/mqtt/mqtt_parser.c reuses
  len_of_varint from the outer Properties Length while parsing each
  SUBSCRIPTION_IDENTI…
severity: high
cvss: 7
cvssVector: 'CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:H'
cwe:
  - CWE-125
vendor: nanomq
product: nanomq
affected:
  - nanomq < 0.24.14
published: '2026-09-18'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:18:35.913'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73863'
references:
  - url: >-
      https://github.com/nanomq/NanoNNG/commit/f888fe39d6691b253ff9aee598ce58bbe449ab6f
    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-pf97-vm7h-q84m'
    label: security-advisories@github.com
  - url: 'https://github.com/nanomq/nanomq/security/advisories/GHSA-pf97-vm7h-q84m'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-24T20:59:35.546596Z'
cvssSource: cna
epss: 0.00443
epssPercentile: 0.35799
ingestedAt: '2026-09-18T16:45:41.410Z'
---

## Overview

NanoMQ is an MQTT broker. Prior to 0.24.14, NanoMQ's broker-side MQTT v5 nmq_subinfo_decode() function in nng/src/sp/protocol/mqtt/mqtt_parser.c reuses len_of_varint from the outer Properties Length while parsing each SUBSCRIPTION_IDENTIFIER. A remote client can send a SUBSCRIBE packet with a multi-byte Properties Length and repeated subscription identifiers, causing get_var_integer() to begin at an incorrect offset and read beyond the heap message buffer. The flaw is reachable through the broker receive path and can crash the broker, while the separately reported topic-option off-by-one occurs later and is not this vulnerability. This issue is fixed in version 0.24.14.

## Remediation

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