V-SFT v6.2.10.0 Stack-Based Buffer Overflow (CVE-2026-32925)

V-SFT versions 6.2.10.0 and earlier are susceptible to a critical stack-based buffer overflow vulnerability identified as CVE-2026-32925. This flaw resides within the VS6ComFile!CV7BaseMap::WriteV7DataToRom function. The vulnerability is triggered when the software processes a specially crafted V7 file. A successful exploit could allow an attacker to execute arbitrary code within the context of the application. This poses a significant risk to systems utilizing affected versions of V-SFT, as it could lead to complete system compromise. The vulnerability was reported to JPCERT/CC and assigned CWE-121, highlighting the classic stack-based buffer overflow nature of the issue.

Attack Chain

1. The attacker crafts a malicious V7 file designed to exploit the buffer overflow in VS6ComFile!CV7BaseMap::WriteV7DataToRom.
2. The user opens the malicious V7 file using a vulnerable version of V-SFT (6.2.10.0 or prior).
3. V-SFT attempts to parse the V7 file, specifically calling the CV7BaseMap::WriteV7DataToRom function.
4. During the WriteV7DataToRom function execution, the crafted V7 file provides input that exceeds the buffer size allocated on the stack.
5. The excessive input overwrites adjacent memory locations on the stack, including the return address.
6. Upon completion of the WriteV7DataToRom function, control is transferred to the overwritten return address.
7. The attacker redirects code execution to a location containing malicious code injected into the process memory.
8. The injected code executes with the privileges of the V-SFT application, potentially leading to complete system compromise.

Impact

Successful exploitation of CVE-2026-32925 allows an attacker to execute arbitrary code on systems running vulnerable versions of V-SFT (6.2.10.0 and prior). This could result in complete system compromise, data theft, or denial of service. The exact number of potential victims is unknown, but the severity is high due to the potential for arbitrary code execution.

Recommendation

• Apply the patch or upgrade to a non-vulnerable version of V-SFT as provided by the vendor (Fujielectric). Refer to the vendor advisory (https://felib.fujielectric.co.jp/en/M10010/M20060/document_detail/5d9dd71d-9494-41a4-aa5c-8e6b8b21066b?region=en-glb).
• Monitor process creation events for V-SFT spawning unusual child processes, which might indicate successful code execution. Utilize the Sigma rule “Detect Suspicious V-SFT Child Processes” to identify such behavior.
• Implement file integrity monitoring for the V-SFT executable and related libraries to detect unauthorized modifications.