CVE-2026-47275
LowCVSS 2.6Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
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. The issue occurs because the code uses variable 'prop' instead of 'will_prop' when iterating over CONNECT properties.
Risk Assessment
The organization is at risk of remote denial of service (DoS) by crashing the NanoMQ client with a single packet. In bridge mode with auto-reconnect, this can lead to an infinite crash loop.
Recommendation
Update nanomq to a version later than 0.24.11 that contains the fix for this vulnerability.
Original NVD description (English source)
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.