CVE-2026-109588: CWE-197 Numeric truncation error in FreeRTOS FreeRTOS-Kernel

This vulnerability involves a numeric truncation error in the MPU buffer authorization check within FreeRTOS-Kernel versions 11.3.0 and 11.3.1 on the Arm Cortex-R82 (Armv8-R AArch64) MPU port. The truncation affects the buffer length validation, which under certain conditions permits an unprivileged task to access privileged kernel memory beyond the validated buffer window through a stream buffer system call. This can lead to a breach of memory protection and potentially compromise confidentiality, integrity, and availability of the system. The vendor advisory from AWS confirms that upgrading to version 11.3.2 or later remediates this issue.

An unprivileged task on MPU-enabled FreeRTOS-Kernel builds (versions 11.3.0 and 11.3.1) can exploit this numeric truncation error to read or write privileged kernel memory beyond the validated buffer window. This can result in full compromise of system confidentiality, integrity, and availability as indicated by the CVSS vector (C:H/I:H/A:H).

Users should upgrade FreeRTOS-Kernel to version 11.3.2 or later to remediate this vulnerability. This is the official fix as stated in the vendor advisory.