Vulnerability in Nanomq

CVE-2026-61633

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 2.0 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.003 (27.3th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 27.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-61633: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-61633?
CVE-2026-61633 is a low-severity vulnerability in Nanomq, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 2.0/10. Published 2026-09-18.
How severe is CVE-2026-61633?
Low severity. CVSS v3 base score is 2.0 out of 10.