NanoMQ up to 0.24.11 MQTT Codec mqtt_codec.c nni_mqttv5_msg_decode_connect prop null pointer dereference

Summaryinfo

A vulnerability has been found in NanoMQ up to 0.24.11 and classified as problematic. This vulnerability affects the function nni_mqttv5_msg_decode_connect of the file mqtt_codec.c of the component MQTT Codec. Performing a manipulation of the argument prop results in null pointer dereference. This vulnerability is identified as CVE-2026-47275. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as problematic has been found in NanoMQ up to 0.24.11. This affects the function nni_mqttv5_msg_decode_connect of the file mqtt_codec.c of the component MQTT Codec. The manipulation of the argument prop with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on availability. The summary by CVE is:

In nanomq versions 0.24.11 and earlier, a NULL pointer dereference in `nni_mqttv5_msg_decode_connect()` allows a malicious MQTT broker to crash any connecting NanoMQ MQTTv5 client (including bridge mode) with a single packet, causing remote denial of service via SIGSEGV. In `nni_mqttv5_msg_decode_connect()` (`mqtt_codec.c:1863`), the code iterates over CONNECT properties using variable `prop` when it should use `will_prop`. When a CONNECT packet has no connect-level properties (`prop == NULL`) but has will properties (`will_prop != NULL`), dereferencing `prop->next` causes SIGSEGV at address `0x38` (NULL + `offsetof(property, next)`). This affects both `nanomq_cli` and **NanoMQ bridge mode** (Core component), as both use the same `mqtt_client.c` receive path. This can lead to remote DoS if a malicious MQTT broker can crash the client process with a single 35-byte packet and persistent DoS if auto-reconnect causes infinite crash loop.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-47275 since 05/19/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Name

• NanoMQ

Version

• 0.24.0
• 0.24.1
• 0.24.2
• 0.24.3
• 0.24.4
• 0.24.5
• 0.24.6
• 0.24.7
• 0.24.8
• 0.24.9
• 0.24.10
• 0.24.11

Website

• Product: https://github.com/nanomq/nanomq/

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