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CVE-2026-61633— NanoMQ: Infinite Loop in UNSUBSCRIBE Decoder Leading to Remote DoS

Quick assessment

Affected
nanomq nanomq
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

NanoMQ 是一个 MQTT 消息代理（broker）。在 0.24.14 版本之前，NanoMQ 客户端函数 （位于 ）在处理格式异常的 UNSUBSCRIBE 数据包时，未能正确处理 读取失败的情况。具体而言，当出现“零长度主题后跟随有尾随数据”的情况时， 可能保持不变，而 却持续增加。这允许恶意的 MQTT 代理使处于连接状态的 MQTT 3.1.1 客户端陷入挂起状态，持续消耗 CPU 和内存资源；在启用了自动重连机制的情况下，恶意代理可反复拒绝服务。代理端的 处理路径不受此问题影响。该问题已在 0.24

CVSS 2.0 · Low EPSS 0.34% · P27

Affected Version Matrix 1

VendorProduct Version RangeStatus
nanomq nanomq < 0.24.14 affected
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I. Basic Information for CVE-2026-61633

Vulnerability Information
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Vulnerability Title
NanoMQ: Infinite Loop in UNSUBSCRIBE Decoder Leading to Remote DoS
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
不可达退出条件的循环(无限循环)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
nanomq nanomq < 0.24.14 -

II. Public POCs for CVE-2026-61633

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III. Intelligence Information for CVE-2026-61633

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Patches & Fixes for CVE-2026-61633 (2)

Vendor Pages for CVE-2026-61633 (1)

Other References for CVE-2026-61633 (1)

Same Patch Batch · nanomq · 2026-09-18 · 3 CVEs total

CVE-2026-73863 7.0 HIGH NanoMQ: Heap-Buffer-Overflow in `nmq_subinfo_decode()` During MQTT v5 SUBSCRIBE Parsing
CVE-2026-44639 3.7 LOW NanoMQ: O(N²) Denial of Service in MQTT v5 Property Parsing

IV. Related Vulnerabilities

Same product: nanomq
Same vendor: nanomq
Same weakness: CWE-835