CVE-2026-47275
nanomq NULL Pointer Dereference in MQTTv5 Client CONNECT Decoder Leading to Remote DoS
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Description
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.
Remediation
No guide yetNo remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.
References (1)
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CVSS
- Attack Vector
- NETWORK
- Complexity
- HIGH
- Privileges
- LOW
- User Interaction
- REQUIRED
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- NONE
- Availability
- LOW
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