CVE-2025-6693: RT-Thread Buffer Overflow Vulnerability

CVE-2025-6693 Overview

CVE-2025-6693 is a memory corruption vulnerability in the RT-Thread real-time operating system through version 5.1.0. The flaw resides in the device management functions sys_device_open, sys_device_read, sys_device_control, sys_device_init, sys_device_close, and sys_device_write within components/drivers/core/device.c. A local attacker with low privileges can manipulate device syscall parameters to corrupt memory. RT-Thread is widely deployed across embedded and Internet of Things (IoT) devices, making the exposure relevant to firmware supply chains. The vendor was contacted before public disclosure but did not respond.

Critical Impact
A local, low-privileged attacker can trigger memory corruption in RT-Thread device syscalls, compromising confidentiality, integrity, and availability of the affected embedded system.

Affected Products

RT-Thread versions up to and including 5.1.0
Embedded firmware built on components/drivers/core/device.c
IoT devices using the RT-Thread device subsystem

Discovery Timeline

2025-06-26 - CVE-2025-6693 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-6693

Vulnerability Analysis

The vulnerability is a memory corruption issue classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer). It affects six device syscall handlers exposed by RT-Thread's driver core: sys_device_open, sys_device_read, sys_device_control, sys_device_init, sys_device_close, and sys_device_write. These functions accept parameters from user-mode callers and operate on kernel device objects without sufficient validation. An attacker running local code on the target device can pass crafted arguments that cause the driver core to read or write outside intended buffer boundaries. Consequences include heap or stack corruption, kernel state manipulation, and potential elevation of privilege on systems that separate user and kernel contexts. Because RT-Thread frequently runs on resource-constrained microcontrollers without modern exploit mitigations, memory corruption often translates directly to arbitrary code execution.

Root Cause

The root cause is missing or insufficient validation of caller-supplied parameters in the device syscall layer of components/drivers/core/device.c. Device object pointers, offsets, and length arguments are consumed without adequate bounds enforcement, allowing out-of-bounds access during read, write, and control operations.

Attack Vector

Exploitation requires local access with low privileges on the RT-Thread system. The attacker invokes one of the affected sys_device_* syscalls with malformed arguments to corrupt memory in the driver core. No user interaction is required. See the RT-Thread GitHub Issue Report and VulDB #313959 for reporter details.

// No verified public exploit code is available for CVE-2025-6693.
// Refer to the GitHub issue and VulDB entries for technical details.

Detection Methods for CVE-2025-6693

Indicators of Compromise

Unexpected crashes, resets, or hard faults on RT-Thread devices during device syscall activity
Kernel panic logs referencing sys_device_open, sys_device_read, sys_device_write, sys_device_control, sys_device_init, or sys_device_close
Anomalous processes invoking device syscalls with unusually large or negative length parameters

Detection Strategies

Enable RT-Thread's kernel assertion and fault logging to capture out-of-bounds accesses at runtime
Perform static analysis of components/drivers/core/device.c on custom RT-Thread builds to confirm patch status
Fuzz the device syscall interface with malformed handles, offsets, and lengths in a lab environment

Monitoring Recommendations

Aggregate device serial and debug logs to a central platform and alert on repeated fault or reset events
Track firmware versions across the IoT fleet and flag any RT-Thread build at or below 5.1.0
Monitor for unauthorized local access or code deployment to embedded devices running RT-Thread

How to Mitigate CVE-2025-6693

Immediate Actions Required

Inventory all firmware images and devices built on RT-Thread and identify versions at or below 5.1.0
Restrict local and physical access to affected embedded devices until a fix is deployed
Remove or restrict untrusted applications that can invoke device syscalls on the target system

Patch Information

No vendor patch has been published at the time of writing. The RT-Thread maintainers did not respond to the reporter's disclosure. Track the RT-Thread GitHub Issue Report for upstream fixes and rebuild affected firmware once a patched commit is available.

Workarounds

Apply input validation patches locally to the sys_device_* handlers in components/drivers/core/device.c before rebuilding firmware
Disable or remove unused device drivers from the RT-Thread build to reduce the attack surface
Enforce least-privilege execution for local applications so untrusted code cannot reach device syscalls

bash

# Identify RT-Thread version in a source tree before rebuilding
grep -R "RT_VERSION" ./include/rtdef.h
grep -R "sys_device_" ./components/drivers/core/device.c