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Vulnerability · Published Mar 30, 2026 · Assigned by GitHub_M

CVE-2026-25627nanomq: OOB Read / Crash (DoS) via Malformed MQTT Remaining Length over WebSocket

Medium 6.5

In plain English

A medium-severity out-of-bounds read in nanomq from nanomq. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities).

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.5%top 57.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. Prior to version 0.24.8, NanoMQ’s MQTT-over-WebSocket transport can be crashed by sending an MQTT packet with a deliberately large Remaining Length in the fixed header while providing a much shorter actual payload. The code path copies Remaining Length bytes without verifying that the current receive buffer contains that many bytes, resulting in an out-of-bounds read (ASAN reports OOB / crash). This is remotely triggerable over the WebSocket listener. This issue has been patched in version 0.24.8.

Affected products (as reported)

VendorProductVersions
nanomq nanomq < 0.24.8

Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References