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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)

Resolution:

This issue has been addressed in FreeRTOS-Kernel version V11.3.2. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

Workarounds:

  • CVE-2026-109587 (MPU region authorization): There is no risk when not using the FreeRTOS MPU on the Arm Cortex-R82 port. Where the Arm Cortex-R82 port and MPU feature are in use, upgrading to the fixed version is the recommended remediation.
  • CVE-2026-109588 (MPU buffer length truncation): There is no risk when not using the FreeRTOS MPU on the Arm Cortex-R82 port. Where the Arm Cortex-R82 port and MPU feature are in use, upgrading to the fixed version is the recommended remediation.

References:

Acknowledgement:

We would like to thank Ada Logics Ltd and Anthropic for collaborating on this issue through the coordinated vulnerability disclosure process.


Please email aws-security@amazon.com with any security questions or concerns.