CVE-2026-54412
HighCVSS 8.2Exploitation Probability (EPSS)
Low risk32th percentile - higher than 32% of all known CVEs
Summary
LiamBindle MQTT-C through version 1.1.6 contains a heap-based out-of-bounds read and integer underflow in the mqtt_unpack_publish_response() function. An unauthenticated remote attacker can crash a subscribed MQTT-C client and potentially disclose adjacent heap memory by sending a crafted PUBLISH packet.
Risk Assessment
This vulnerability may lead to application crashes and exposure of sensitive data in memory, posing a risk to the security of systems using MQTT-C.
Recommendation
It is recommended to update to the latest version of MQTT-C to mitigate this vulnerability and to monitor MQTT traffic for potential attack attempts.
Original NVD description (English source)
LiamBindle MQTT-C through version 1.1.6 contains a heap-based out-of-bounds read and integer underflow in the mqtt_unpack_publish_response() function in src/mqtt.c that allows a remote unauthenticated attacker controlling an MQTT broker - or able to inject MQTT traffic into an unencrypted session - to crash a subscribed MQTT-C client and potentially disclose adjacent heap memory by sending a single crafted PUBLISH packet. The function validates only that the fixed-header remaining_length is at least 4, then reads the 16-bit topic_name_size field from the broker-controlled packet and advances the parse pointer by that value without verifying that topic_name_size plus the surrounding overhead fits within remaining_length; it subsequently computes application_message_size as remaining_length - topic_name_size - 2 (QoS 0) or - 4 (QoS greater than 0) in unsigned arithmetic, producing an integer underflow that is then passed to memmove(). A PUBLISH packet with topic_name_size = 0xFFFF and remaining_length = 7 advances the parse pointer 65535 bytes past the receive buffer (out-of-bounds read) and causes an application_message_size near 2^32, crashing the process when the resulting memmove() is executed.