Executive brief
FreeRTOS-Kernel is a real-time operating system kernel used in embedded systems and IoT devices. A validation flaw in secure context memory allocation allows local attackers to corrupt secure-world heap metadata through an undersized stack parameter, potentially compromising the integrity of security-critical operations and sensitive data in TrustZone environments.
Technical details
The vulnerability is an input validation flaw in the SecureContext_AllocateContext function within ARMv8-M secure-side ports. When allocating secure context memory, the function fails to validate that the requested stack size meets a minimum threshold (the stack seal size), allowing an attacker with local access to supply an undersized stack parameter. This results in an out-of-bounds write that corrupts secure-world heap metadata. The vulnerability affects FreeRTOS-Kernel versions before 11.3.1. The fix adds validation to ensure the secure stack size plus seal size does not overflow before allocation, and rejects stack sizes smaller than the seal size.
Affected products
- FreeRTOS FreeRTOS-Kernel before 11.3.1
Timeline
- 2026-08-21: disclosed
- 2026-08-21: patched: Version 11.3.1 released with validation added to SecureContext_AllocateContext