CVE-2025-61856: Fujielectric Monitouch V-sft Overflow

CVE-2025-61856 Overview

CVE-2025-61856 is a stack-based buffer overflow [CWE-121] in the VS6ComFile!CV7BaseMap::WriteV7DataToRom function of Fuji Electric V-SFT v6.2.7.0 and earlier. V-SFT is engineering software used to configure Monitouch human-machine interface (HMI) panels deployed in industrial control environments. An attacker who convinces an engineer to open a specially crafted V-SFT project file can trigger memory corruption that may result in information disclosure, application abnormal termination (ABEND), or arbitrary code execution on the engineering workstation.

Critical Impact
Successful exploitation grants code execution in the context of the V-SFT process, providing a foothold on engineering workstations that interact with operational technology (OT) assets.

Affected Products

Fuji Electric Monitouch V-SFT v6.2.7.0
Fuji Electric Monitouch V-SFT versions prior to v6.2.7.0
Engineering workstations running V-SFT v6 configuration software

Discovery Timeline

2025-10-10 - CVE-2025-61856 published to NVD
2025-10-27 - Last updated in NVD database

Technical Details for CVE-2025-61856

Vulnerability Analysis

The vulnerability resides in the CV7BaseMap::WriteV7DataToRom method exported by VS6ComFile, a component of the V-SFT v6 engineering suite. When the application parses a V-SFT project file, the routine writes attacker-controllable data into a fixed-size stack buffer without enforcing bounds on the source length. The result is a classic stack-based buffer overflow that corrupts adjacent stack frame data, including saved return addresses and structured exception handler records on Windows.

Because V-SFT is a desktop engineering tool, the attack vector is local: an operator must open the malicious file. However, V-SFT project files are routinely exchanged between integrators, OEMs, and plant engineers, which provides a realistic delivery path through email attachments, shared drives, or USB media. Exploitation requires no authentication and only a single user interaction.

Root Cause

The root cause is missing or insufficient length validation when copying parsed file content into a stack-allocated buffer inside CV7BaseMap::WriteV7DataToRom. The function trusts size or offset fields embedded in the input file, allowing a crafted file to drive a write past the end of the destination buffer.

Attack Vector

An attacker crafts a malformed V-SFT project file containing oversized or malformed records that flow into the vulnerable routine. The file is delivered to a target engineer through social engineering, supply-chain delivery, or a compromised file share. Opening the file in a vulnerable V-SFT installation triggers the overflow. With reliable control of execution flow, the attacker achieves arbitrary code execution under the user account running V-SFT, which on engineering workstations is frequently a privileged or interactive account with network access to HMI and PLC assets.

No public proof-of-concept or in-the-wild exploitation has been reported, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. See the JVN Security Vulnerability Report for advisory details.

Detection Methods for CVE-2025-61856

Indicators of Compromise

Unexpected crashes or abnormal termination (ABEND) of V-SFT.exe or processes loading VS6ComFile.dll shortly after a project file is opened
Creation of child processes (for example cmd.exe, powershell.exe, rundll32.exe) spawned by the V-SFT process tree
V-SFT project files received from untrusted external sources or staged in user temp and download directories prior to a crash event

Detection Strategies

Monitor for Windows Error Reporting (WER) and application crash events naming the V-SFT process or VS6ComFile module, which indicate a likely overflow attempt
Alert on V-SFT writing to or executing from unusual paths such as %TEMP%, %APPDATA%, or removable media
Hunt for command-and-control or reconnaissance behavior originating from engineering workstations that host V-SFT

Monitoring Recommendations

Inventory and tag all hosts running V-SFT v6 so that endpoint telemetry can be filtered for OT-adjacent assets
Forward process, image-load, and crash telemetry from engineering workstations into a centralized data lake for retrospective hunting
Track file transfers of V-SFT project extensions across email gateways, web proxies, and removable media controls

How to Mitigate CVE-2025-61856

Immediate Actions Required

Identify all systems running Fuji Electric V-SFT v6.2.7.0 or earlier and prioritize them for patching
Restrict V-SFT usage to dedicated engineering workstations isolated from general-purpose email and web browsing
Instruct engineers to open V-SFT project files only from verified internal sources and to validate file provenance before opening

Patch Information

Fuji Electric has released updated V-SFT v6 software addressing the buffer overflow. Download the fixed version from the Fuji Electric Monitouch Download Page and upgrade all affected installations. Confirm version 6.2.7.0 or later after installation.

Workarounds

Apply application allowlisting to prevent unsigned or unexpected child processes from launching under V-SFT.exe
Enforce least privilege so V-SFT runs without local administrator rights, limiting post-exploitation impact
Block inbound V-SFT project files at email and web gateways unless they originate from a known-good sender or repository
Segment engineering workstations from corporate IT and the wider OT network using firewalls aligned with the Purdue model

bash

# Example: enumerate V-SFT installations across Windows endpoints via PowerShell remoting
Invoke-Command -ComputerName (Get-Content .\eng-workstations.txt) -ScriptBlock {
    Get-ItemProperty 'HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*' |
        Where-Object { $_.DisplayName -like '*V-SFT*' } |
        Select-Object PSComputerName, DisplayName, DisplayVersion, InstallLocation
}