CVE-2026-109587 in FreeRTOS
Summary
by MITRE • 10/16/2026
Incorrect authorization in the Arm Cortex-R82 (Armv8-R AArch64) MPU port in FreeRTOS-Kernel V11.3.0 and V11.3.1 might allow an unprivileged task on MPU-enabled builds to read and write privileged kernel memory outside the regions assigned to it, via a buffer argument passed to an MPU system call.
To remediate this issue, users should upgrade to version V11.3.2 or later.
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Analysis
by VulDB Data Team • 10/16/2026
The vulnerability identified in FreeRTOS-Kernel versions 11.3.0 and 11.3.1 represents a critical failure in memory protection enforcement within the Arm Cortex-R82 processor environment, specifically affecting builds that utilize the Memory Protection Unit (MPU) with AArch64 architecture support. This flaw stems from an incorrect authorization mechanism embedded in the MPU port configuration of the real-time operating system kernel. In secure and safety-critical systems running on ARMv8-R architectures, the MPU is responsible for enforcing strict boundaries between different memory regions to prevent unauthorized access. The Cortex-R82 processor relies heavily on these hardware-enforced protections to isolate tasks from one another and to shield privileged kernel data structures from unprivileged application code. When this isolation mechanism fails due to a logic error in how system calls handle buffer arguments, the fundamental security model of the operating system is compromised, allowing for potential privilege escalation or unauthorized memory manipulation that bypasses standard software-based access controls.
The technical nature of this flaw involves a specific interaction between an unprivileged task and the kernel through an MPU-enabled system call interface. Under normal operation, when an unprivileged task invokes a system call to interact with the kernel, it passes buffer arguments that define the data regions involved in the transaction. The operating system is responsible for validating these buffers against the memory permissions assigned to the calling task via the MPU configuration registers. In versions 11.3.0 and 11.3.1 of FreeRTOS-Kernel, this validation process contains a logical defect where the authorization check does not correctly restrict access to only those regions explicitly permitted by the MPU settings for that specific task. Consequently, an attacker or malicious code executing within an unprivileged task context can craft a buffer argument that points to memory addresses outside its assigned region but still falls within privileged kernel space. Because the system call handler fails to enforce the boundary constraints properly during this interaction, it permits read and write operations into these protected areas, effectively bypassing the hardware-enforced isolation intended by the MPU configuration.
The operational impact of this vulnerability is severe, particularly in environments where FreeRTOS is deployed for safety-critical applications such as automotive control units, industrial automation systems, or medical devices. By allowing an unprivileged task to read privileged kernel memory, an attacker can potentially extract sensitive information including cryptographic keys, authentication tokens, or internal state variables that are critical for system integrity. Furthermore the ability to write to these regions enables arbitrary code execution or logic manipulation within the kernel itself. This could lead to a complete compromise of the host system, allowing the attacker to hijack control flow, disable security features, or cause denial-of-service conditions by corrupting essential data structures. In multi-tasking environments where different tasks operate at varying trust levels, this flaw effectively nullifies the separation between low-privilege application code and high-privilege kernel services, undermining the entire principle of least privilege that underpins secure embedded system design.
This vulnerability aligns with CWE-269 Improper Privilege Management and CWE-787 Out-of-bounds Write in terms of its root cause and effect, as it involves unauthorized access to memory regions outside the allocated boundaries due to insufficient checks on input parameters passed to privileged functions. From a tactical perspective, this flaw facilitates lateral movement within the system by allowing an attacker to escalate privileges from user space to kernel space without requiring exploitation of additional software bugs or hardware errata. It also relates to ATT&CK techniques involving privilege escalation and memory manipulation, highlighting the importance of rigorous input validation in operating system kernels that interface with hardware security features like MPUs. The failure here is not merely a coding error but a systemic breakdown in how the OS leverages hardware-assisted protection mechanisms, which are often relied upon for achieving compliance with stringent safety standards such as ISO 26262 or IEC 61508 where memory isolation is a mandatory requirement.
To remediate this issue and restore the integrity of the memory protection model, users must upgrade to FreeRTOS-Kernel version V11.3.2 or any later release that incorporates the corrected authorization logic. This update addresses the specific defect in how buffer arguments are validated against MPU region permissions during system call execution. Organizations relying on older versions should prioritize this patch deployment across all affected deployments, particularly those running on Arm Cortex-R82 processors with AArch64 support enabled for memory protection. Additionally, developers implementing FreeRTOS in new projects should ensure they utilize the latest stable kernel version and conduct thorough security audits of their MPU configuration to guarantee that task boundaries are correctly defined and enforced by both the hardware and the operating system software layer. Regular updates and adherence to vendor-recommended versions are essential practices to mitigate risks associated with such critical infrastructure vulnerabilities.