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CVE-2026-73863— NanoMQ: Heap-Buffer-Overflow in `nmq_subinfo_decode()` During MQTT v5 SUBSCRIBE Parsing

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 是一款 MQTT 消息代理（Broker）。在 0.24.14 版本之前，NanoMQ 代理端的 MQTT v5 函数 （位于 ）在解析每个 时，错误地复用了外层的“Properties Length”中的 。远程客户端可以发送一个带有多字节 Properties Length 和重复订阅标识符的 SUBSCRIBE 数据包，导致 从错误的偏移量开始读取，从而越界读取堆消息缓冲区。该漏洞可通过代理的接收路径触发，可能导致代理崩溃。另外报告的“主题选项”中的 off-by-one 错误发生在之后，且与当

CVSS 7.0 · High EPSS 0.35% · P29

Affected Version Matrix 1

VendorProduct Version RangeStatus
nanomq nanomq < 0.24.14 affected
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I. Basic Information for CVE-2026-73863

Vulnerability Information
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Vulnerability Title
NanoMQ: Heap-Buffer-Overflow in `nmq_subinfo_decode()` During MQTT v5 SUBSCRIBE Parsing
Source: CVE Program / CVE List V5
Vulnerability Description
NanoMQ is an MQTT broker. Prior to 0.24.14, NanoMQ's broker-side MQTT v5 nmq_subinfo_decode() function in nng/src/sp/protocol/mqtt/mqtt_parser.c reuses len_of_varint from the outer Properties Length while parsing each SUBSCRIPTION_IDENTIFIER. A remote client can send a SUBSCRIBE packet with a multi-byte Properties Length and repeated subscription identifiers, causing get_var_integer() to begin at an incorrect offset and read beyond the heap message buffer. The flaw is reachable through the broker receive path and can crash the broker, while the separately reported topic-option off-by-one occurs later and is not this vulnerability. This issue is fixed in version 0.24.14.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
nanomq nanomq < 0.24.14 -

II. Public POCs for CVE-2026-73863

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III. Intelligence Information for CVE-2026-73863

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Patches & Fixes for CVE-2026-73863 (2)

Vendor Pages for CVE-2026-73863 (1)

Other References for CVE-2026-73863 (1)

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

CVE-2026-44639 3.7 LOW NanoMQ: O(N²) Denial of Service in MQTT v5 Property Parsing
CVE-2026-61633 2.0 LOW NanoMQ: Infinite Loop in UNSUBSCRIBE Decoder Leading to Remote DoS

IV. Related Vulnerabilities

Same product: nanomq
Same vendor: nanomq
Same weakness: CWE-125