CVE-2021-45934: 
Homebrew vulnerability analysis and mitigation

wolfSSL wolfMQTT version 1.9 contains a heap-based buffer overflow vulnerability in the MqttClientDecodePacket function, which is called from MqttClientHandlePacket and MqttClient_WaitType. The vulnerability was discovered and reported through the OSS-Fuzz program (OSS-Fuzz Report).

The vulnerability is classified as a heap-buffer-overflow WRITE 1 condition that occurs in the MqttClientDecodePacket function. The issue is triggered through a sequence of function calls: MqttClientDecodePacket -> MqttClientHandlePacket -> MqttClientWaitType. The vulnerability has been assigned a CVSS v3.1 Base Score of 5.5 (MEDIUM) with the vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H (NVD).

The heap-based buffer overflow vulnerability could potentially lead to system crashes or denial of service conditions. The CVSS scoring indicates that while confidentiality and integrity impacts are not present, there is a high impact on system availability. The vulnerability requires local access and user interaction to be exploited.

The vulnerability has been fixed in a subsequent commit (84d4b53122e0fa0280c7872350b89d5777dabbb2) to the wolfMQTT repository. Users should upgrade from version 1.9 to a patched version of the software to mitigate this vulnerability (Patch).