Description
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: 2026-09-18
Score: 2 Low
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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History

Fri, 18 Sep 2026 23:45:00 +0000

Type Values Removed Values Added
First Time appeared Nanomq
Nanomq nanomq
Vendors & Products Nanomq
Nanomq nanomq

Fri, 18 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 18 Sep 2026 16:30:00 +0000

Type Values Removed Values Added
Description 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.
Title NanoMQ: Infinite Loop in UNSUBSCRIBE Decoder Leading to Remote DoS
Weaknesses CWE-835
References
Metrics cvssV3_1

{'score': 2, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-18T17:26:49.956Z

Reserved: 2026-07-10T17:38:57.111Z

Link: CVE-2026-61633

cve-icon Vulnrichment

Updated: 2026-09-18T17:26:42.861Z

cve-icon NVD

Status : Deferred

Published: 2026-09-18T17:16:58.340

Modified: 2026-09-18T18:17:09.433

Link: CVE-2026-61633

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-19T17:00:12Z

Weaknesses
  • CWE-835

    Loop with Unreachable Exit Condition ('Infinite Loop')