Summary
An incorrect authorization vulnerability in the Arm Cortex-R82 MPU port for FreeRTOS-Kernel may allow an unprivileged task to read or modify privileged kernel memory.
The issue becomes risky on MPU-enabled builds when attacker-controlled or insufficiently validated buffer arguments are passed to an MPU system call.
An incorrect authorization vulnerability in the Arm Cortex-R82 MPU port for FreeRTOS-Kernel may allow an unprivileged task to read or modify privileged kernel memory.
The issue becomes risky on MPU-enabled builds when attacker-controlled or insufficiently validated buffer arguments are passed to an MPU system call.
Affected context
This vulnerability affects FreeRTOS-Kernel deployments using the Arm Cortex-R82, Armv8-R AArch64 MPU port on MPU-enabled builds. It occurs when an unprivileged task can invoke an MPU system call with a buffer argument that is not adequately checked against the task's permitted memory regions.
This vulnerability affects FreeRTOS-Kernel deployments using the Arm Cortex-R82, Armv8-R AArch64 MPU port on MPU-enabled builds. It occurs when an unprivileged task can invoke an MPU system call with a buffer argument that is not adequately checked against the task's permitted memory regions.
Exploit preconditions
- Attack surface: MPU system-call interfaces exposed to application tasks
- Required access: Execution as an unprivileged task within the affected FreeRTOS environment
- Trigger point: Passing a buffer argument to an MPU system call
- Why exploitation is possible: Authorization and memory-region validation may fail to ensure that the buffer remains within regions assigned to the calling task
- Attack surface: MPU system-call interfaces exposed to application tasks
- Required access: Execution as an unprivileged task within the affected FreeRTOS environment
- Trigger point: Passing a buffer argument to an MPU system call
- Why exploitation is possible: Authorization and memory-region validation may fail to ensure that the buffer remains within regions assigned to the calling task
Why this happens
The underlying bug is an authorization failure in memory-access enforcement. The MPU system-call path does not sufficiently constrain a buffer supplied by an unprivileged task to the task's authorized memory regions.
This maps to CWE-863: Incorrect Authorization, because the system permits an operation on protected resources without correctly verifying whether the requesting task has the required authority.
The underlying bug is an authorization failure in memory-access enforcement. The MPU system-call path does not sufficiently constrain a buffer supplied by an unprivileged task to the task's authorized memory regions.
This maps to CWE-863: Incorrect Authorization, because the system permits an operation on protected resources without correctly verifying whether the requesting task has the required authority.
Potential impact
- An unprivileged task may read privileged kernel memory
- An unprivileged task may modify kernel memory or control data
- The vulnerability could enable privilege escalation within the device
- System integrity, isolation boundaries, or sensitive data may be compromised
- An attacker could cause denial of service or alter security-critical runtime behavior
- An unprivileged task may read privileged kernel memory
- An unprivileged task may modify kernel memory or control data
- The vulnerability could enable privilege escalation within the device
- System integrity, isolation boundaries, or sensitive data may be compromised
- An attacker could cause denial of service or alter security-critical runtime behavior
General mitigation guidance
Mitigation focuses on enforcing authorization at every MPU system-call boundary and ensuring that memory references are validated against the calling task's effective permissions.
Common defensive patterns include:
- Use secure, vendor-supported maintenance releases that contain the relevant correction
- Validate buffer addresses, lengths, and access directions before privileged operations
- Verify that complete buffers remain within regions authorized for the calling task
- Avoid trusting caller-supplied pointers or metadata as proof of authorization
- Minimize the privileges and memory visibility granted to application tasks
- Apply defense-in-depth checks in both system-call wrappers and privileged kernel handlers
Mitigation focuses on enforcing authorization at every MPU system-call boundary and ensuring that memory references are validated against the calling task's effective permissions.
Common defensive patterns include:
- Use secure, vendor-supported maintenance releases that contain the relevant correction
- Validate buffer addresses, lengths, and access directions before privileged operations
- Verify that complete buffers remain within regions authorized for the calling task
- Avoid trusting caller-supplied pointers or metadata as proof of authorization
- Minimize the privileges and memory visibility granted to application tasks
- Apply defense-in-depth checks in both system-call wrappers and privileged kernel handlers
How teams detect issues like this
Organizations can detect related authorization flaws through:
- Static analysis rules for unchecked pointer, length, and region arguments in privileged interfaces
- Code review checks for MPU system calls that validate only buffer starts or omit overflow handling
- Unit and integration tests using boundary, cross-region, and privileged-address inputs
- Policy enforcement requiring explicit authorization checks for every task-to-kernel memory operation
- Runtime monitoring for unexpected unprivileged accesses to kernel-owned memory
Automated security review tools may help identify missing authorization checks and unsafe memory-range validation.
Organizations can detect related authorization flaws through:
- Static analysis rules for unchecked pointer, length, and region arguments in privileged interfaces
- Code review checks for MPU system calls that validate only buffer starts or omit overflow handling
- Unit and integration tests using boundary, cross-region, and privileged-address inputs
- Policy enforcement requiring explicit authorization checks for every task-to-kernel memory operation
- Runtime monitoring for unexpected unprivileged accesses to kernel-owned memory
Automated security review tools may help identify missing authorization checks and unsafe memory-range validation.
