CVE-2026-61633Public exploitNetwork attack vectorHinoki check available

Client hang via stalled UNSUBSCRIBE topic parsing

Published Sep 18, 2026 · Updated Sep 18, 2026

Denial of service in NanoMQ before 0.24.14 allows remote attackers controlling an MQTT broker to hang MQTT 3.1.1 clients. The nni_mqtt_msg_decode_unsubscribe() loop ignores a failed read_uint16(), so a zero-length topic with trailing data leaves buf.curpos unchanged as topic_count grows. Exploitation requires the NanoMQ client, including bridge mode, to connect to an attacker-controlled broker; automatic reconnection can repeat the hang.

CVSS severity2.0
Low
EPSS probability0.34%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Denial of service in NanoMQ before 0.24.14 allows remote attackers controlling an MQTT broker to hang MQTT 3.1.1 clients. The nni_mqtt_msg_decode_unsubscribe() loop ignores a failed read_uint16(), so a zero-length topic with trailing data leaves buf.curpos unchanged as topic_count grows. Exploitation requires the NanoMQ client, including bridge mode, to connect to an attacker-controlled broker; automatic reconnection can repeat the hang.

The record

CVE
CVE-2026-61633
Published
Sep 18, 2026
Updated
Sep 18, 2026
Vendor
EMQ Technologies
Product
NanoMQ
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Sep 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.24.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

EMQ Technologies · NanoMQversion=< 0.24.14

Published CVSS scores

2.0GitHubCVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

Public exploit references

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Technologies

Your stack

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Your stack

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