The flaw is a numeric truncation of the buffer length in the MPU buffer authorization check, which is a classic example of CWE‑125 (Buffer Under-read), CWE‑197 (Numeric Truncation) and CWE‑787 (Out-of-bounds Write). This weakness allows an unprivileged task on MPU-enabled FreeRTOS‑Kernel builds to read or modify privileged kernel memory beyond the intended buffer window when using a stream buffer system call. The consequence is potential arbitrary code execution or denial of service, as the attacker can corrupt critical kernel data.

FreeRTOS‑Kernel versions 11.3.0 and 11.3.1, compiled for Arm Cortex‑R82 (Armv8‑R AArch64) with MPU support. The vulnerability targets unprivileged tasks that perform stream buffer operations on systems where the MPU port is enabled.

The CVSS score of 9.3 marks this as a high severity vulnerability. The EPSS score is not available, so the probability of exploitation remains uncertain. The vulnerability is not listed in the CISA KEV catalog. It is inferred that the attack vector is local: an attacker must drop an unprivileged task or otherwise influence a task on the affected system. If successful, the malicious task could read or write privileged kernel memory through the stream buffer API, leading to privilege escalation or system compromise.