CVE-2026-77234 in FreeRTOS
Summary
by MITRE • 08/21/2026
Improper input validation in FreeRTOS-Kernel before 11.3.1 might allow an unprivileged task on MPU-enabled ports to execute code in privileged kernel context. To remediate this issue, users should upgrade to version 11.3.1 or later.
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Analysis
by VulDB Data Team • 08/21/2026
The vulnerability identified as improper input validation within the FreeRTOS-Kernel prior to version 11.3.1 represents a critical security flaw that undermines the fundamental isolation mechanisms provided by Memory Protection Unit enabled ports. In embedded systems utilizing FreeRTOS, the operating system relies on strict privilege separation between unprivileged application tasks and privileged kernel threads to maintain system integrity. When an MPU is configured, it enforces memory access boundaries based on execution privileges, ensuring that user-level code cannot arbitrarily read or write protected kernel memory regions. However, in versions preceding 11.3.1, the kernel failed to adequately validate certain inputs passed from unprivileged tasks during specific API calls or context switches. This lack of rigorous validation allows an attacker who has gained access to a low-privilege task to manipulate internal kernel structures or trigger execution paths that bypass MPU restrictions.
The technical core of this flaw lies in the insufficient checks performed before transitioning control back to privileged mode. An unprivileged task can craft specific arguments or state conditions that cause the kernel to execute code with elevated privileges without proper authorization verification. This effectively allows privilege escalation, where a process operating at user level gains root-like access within the RTOS environment. Such an outcome is particularly dangerous in safety-critical applications because it breaks the trust boundary assumed by secure boot and runtime integrity mechanisms. The attacker can potentially modify kernel variables, alter task scheduling parameters, or inject malicious code into privileged memory spaces that are normally inaccessible, leading to a complete compromise of the system's security posture.
From an operational impact perspective, this vulnerability enables remote or local attackers to achieve arbitrary code execution within the most sensitive parts of the operating system. If exploited successfully, it can lead to data exfiltration from protected memory regions, denial of service through kernel panic induced by corrupted state variables, or persistent backdoor installation that survives reboots if combined with other flaws in the firmware update mechanism. In IoT devices and industrial control systems where FreeRTOS is prevalent, such a breach could allow an adversary to take full control over connected hardware, manipulate sensor data, disrupt critical processes, or use the compromised device as a pivot point for further network attacks. The severity is amplified by the fact that many embedded deployments run with minimal security hardening due to resource constraints, making them highly susceptible to exploitation once this privilege escalation vector is identified.
This issue aligns closely with CWE-20 Improper Input Validation and CWE-787 Out-of-bounds Write if memory corruption occurs during the invalid access, as well as ATT&CK technique T1068 Exploitation for Privilege Escalation. The failure to enforce expected constraints on input data allows an actor to bypass intended restrictions, which is a classic pattern in embedded system vulnerabilities. Mitigation strategies must prioritize immediate patching of all affected systems by upgrading the FreeRTOS-Kernel component to version 11.3.1 or any later release where these validation checks have been rigorously implemented and tested. Additionally, developers should review their MPU configuration settings to ensure that memory regions are correctly mapped with appropriate access permissions for both privileged and unprivileged contexts. Implementing runtime monitoring tools can also help detect anomalous behavior indicative of exploitation attempts, providing an additional layer of defense in depth while the underlying software is updated. Regular security audits focusing on input handling routines within kernel APIs are recommended to prevent similar vulnerabilities from being introduced during future development cycles.