CVE-2026-115679 in MDK-Middleware
Summary
by MITRE • 10/26/2026
Arm Keil MDK-Middleware 8.3.0 may allow out-of-bounds reads and writes to the FTP Server RX Buffer
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Analysis
by VulDB Data Team • 10/26/2026
The vulnerability identified in Arm Keil MDK-Middleware version 8.3.0 pertains specifically to the FTP server component, exposing a critical memory safety flaw within its receive buffer handling logic. This middleware is widely utilized by embedded systems developers for implementing network connectivity and file transfer capabilities on ARM-based microcontrollers. The core issue lies in how the application processes incoming data packets destined for the FTP service. Specifically, the implementation fails to adequately validate the length of incoming data against the allocated size of the receive buffer before copying or processing that data. This lack of rigorous boundary checking creates a scenario where an attacker can manipulate network traffic to trigger either out-of-bounds reads or writes, depending on the specific state of the server and the nature of the crafted packet.
From a technical perspective, this flaw is classified under CWE-125 for out-of-bounds read and CWE-787 for out-of-bounds write, which are among the most dangerous classes of memory corruption vulnerabilities in C-based embedded environments. When an attacker sends a specially crafted FTP command or data payload that exceeds the expected buffer limits, the software may attempt to access memory locations adjacent to the intended buffer space. In the case of an out-of-bounds read, this could lead to information disclosure, allowing the extraction of sensitive stack contents, cryptographic keys, or other confidential data residing in nearby memory regions. Conversely, if the vulnerability allows for an out-of-bounds write, it presents a far more severe risk by enabling arbitrary code execution. By carefully crafting the overflow payload, an attacker can overwrite critical control structures such as return addresses on the call stack or function pointers within global offset tables, thereby hijacking the flow of execution and gaining full control over the compromised device.
The operational impact of this vulnerability is significant for any organization deploying embedded devices that rely on Arm Keil MDK-Middleware for FTP functionality. Since many IoT devices operate in untrusted network environments or are exposed to public internet services, they are particularly susceptible to remote exploitation. An attacker with access to the same network segment as the target device could exploit this flaw without authentication if the FTP server is configured to allow anonymous login or lacks proper access controls. Successful exploitation would result in a complete compromise of the embedded system's integrity and confidentiality. This could lead to unauthorized modification of firmware, theft of proprietary data stored on the device, or the use of the compromised node as part of a larger botnet for distributed denial-of-service attacks. The persistence of such vulnerabilities in widely used middleware libraries amplifies the risk across entire industries dependent on ARM architecture.
Mitigation strategies must address both immediate remediation and long-term security hygiene. The primary solution is to update the Arm Keil MDK-Middleware package to a version that includes patches for this specific buffer handling issue, ensuring that proper bounds checking is implemented before any data is copied into the receive buffer. Developers should also review their FTP server configurations to disable anonymous access if it is not strictly required and enforce strong authentication mechanisms. Furthermore, implementing network-level security controls such as firewalls or intrusion detection systems can help filter out malformed packets before they reach the vulnerable application layer. For developers who cannot immediately update the middleware, applying input validation logic at the application level to truncate oversized requests may provide a temporary workaround, though this is less reliable than patching the underlying library. Regular code audits focusing on memory management practices and adherence to secure coding standards like MISRA C are essential for preventing similar vulnerabilities in future development cycles.