CVE-2026-109587 & CVE-2026-109588 - Issue with FreeRTOS-Kernel

Bulletin ID: 2026-138-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 10/16/2026 10:00 AM PDT Description: FreeRTOS-Kernel is a real-time operating system kernel for microcontrollers and small microprocessors, distributed by Amazon. AWS identified two issues with the FreeRTOS-Kernel Arm Cortex-R82 (Armv8-R AArch64) MPU port, affecting multiple versions. CVE-2026-109587: incorrect authorization in the Arm Cortex-R82 MPU port. On MPU-enabled builds, the port does not correctly enforce the memory-region boundaries assigned to an unprivileged task when it passes a buffer argument to an MPU system call. Under certain conditions, an unprivileged task might read and write privileged kernel memory outside the regions assigned to it. This issue affects Arm Cortex-R82 builds with configENABLE_MPU=1; applications that do not use the FreeRTOS MPU are not affected. CVE-2026-109588: numeric truncation in the MPU buffer authorization check on the Arm Cortex-R82 MPU port. On MPU-enabled builds, the buffer-length validation does not correctly account for the full length of a buffer passed to a stream buffer system call. Under certain conditions, an unprivileged task might read or write privileged kernel memory beyond the validated buffer window. This issue affects Arm Cortex-R82 builds with configENABLE_MPU=1; applications that do not use the FreeRTOS MPU are not affected. Impacted versions:

• CVE-2026-109587 (MPU region authorization): V11.3.0 and V11.3.1 (Arm Cortex-R82 builds with configENABLE_MPU=1)
• CVE-2026-109588 (MPU buffer length truncation): V11.3.0 and V11.3.1 (Arm Cortex-R82 builds with configENABLE_MPU=1) Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.