CVE-2026-25627: Emqx Nanomq

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

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

• Emqx Nanomq: before 0.24.8 (fixed in 0.24.8)

Published 2026-03-30. Last modified 2026-06-17.