CVE-2026-61633: Nanomq

Low severity, CVSS 2.0. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Nanomq Nanomq: before 0.24.14 (fixed in 0.24.14)

Published 2026-09-18. Last modified 2026-09-18.