This vulnerability involves an out-of-bounds read in the MQTT v5.0 property parser component of FreeRTOS coreMQTT prior to version 5.0.1. Specifically, the parser lacks proper bounds validation, which allows a malicious MQTT broker to send a specially crafted packet that triggers a denial of service by causing the software to read memory outside of intended bounds. The vulnerability is identified as CWE-125 and has a CVSS 3.1 base score of 7.5 (high severity) with network attack vector, low attack complexity, no privileges or user interaction required, and impacts availability only. The vendor advisory from AWS recommends upgrading to coreMQTT v5.0.1 to address this issue.

An attacker controlling an MQTT broker can exploit this vulnerability to cause a denial of service on clients using coreMQTT version 5.0.0 by sending a crafted MQTT packet that triggers an out-of-bounds read. This results in application or system crashes, impacting availability. There is no indication of confidentiality or integrity impact. No known exploits in the wild have been reported at this time.

Users should upgrade to FreeRTOS coreMQTT version 5.0.1, which contains the fix for this vulnerability. The vendor advisory from AWS explicitly states that upgrading to v5.0.1 remediates the issue. Patch status is confirmed by the vendor advisory. No additional mitigations are specified or required beyond applying this update.