CVE-2026-21888: Emqx Nanomq

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. MQTT v5 Variable Byte Integer parsing out-of-bounds: get_var_integer() accepts 5-byte varints without bounds checks; reliably triggers OOB read / crash when built with ASan. This affects 0.24.6 and earlier.

Affected products

• Emqx Nanomq: up to and including 0.24.6

Published 2026-03-11. Last modified 2026-06-17.