CVE-2026-61633

What it is

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.

At a glance

Exploitability

Can be exploited over the network with an admin-level account, but needs a user to act. Limited direct impact.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-18 17:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-18 18:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.3% in the next 30 days (EPSS).
• Severity: 2.0 LOW (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-09-18 17:16 UTC

Last modified

2026-09-18 18:17 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-835

Record status

Deferred

Attack profile CVSS 3.1 · 2.0

Attack vector

Network

Complexity

High

Privileges needed

High

User interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-61633.md and follow it. Check whether this project is affected by CVE-2026-61633. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge