CVE-2025-61857: Fujielectric Monitouch V-sft RCE Flaw

CVE-2025-61857 Overview

CVE-2025-61857 is an out-of-bounds write vulnerability in Fuji Electric's V-SFT v6 screen configuration software. The flaw resides in the VS6ComFile!CItemExChange::WinFontDynStrCheck function and affects versions 6.2.7.0 and earlier. An attacker who convinces a user to open a specially crafted V-SFT project file can trigger memory corruption. Successful exploitation may result in information disclosure, an abnormal end (ABEND) condition, or arbitrary code execution in the context of the user running the application. The issue is tracked under CWE-787: Out-of-bounds Write and was published through the JVN Security Advisory.

Critical Impact
Opening a malicious V-SFT file can lead to arbitrary code execution on an engineering workstation supporting industrial human-machine interface (HMI) deployments.

Affected Products

Fuji Electric Monitouch V-SFT v6 versions 6.2.7.0 and earlier
VS6ComFile component (CItemExChange::WinFontDynStrCheck function)
V-SFT project files (.V8, .V9, .V10 series formats handled by V-SFT v6)

Discovery Timeline

2025-10-10 - CVE-2025-61857 published to NVD
2025-10-27 - Last updated in NVD database

Technical Details for CVE-2025-61857

Vulnerability Analysis

The vulnerability is an out-of-bounds write classified as [CWE-787]. It resides in the WinFontDynStrCheck method of the CItemExChange class within the VS6ComFile module. This routine processes Windows font dynamic string data embedded inside V-SFT project files. When the function processes a crafted file with malformed length or offset fields, it writes data past the bounds of an allocated buffer. The corrupted memory region can include adjacent heap structures, function pointers, or virtual table references used by the application.

Exploitation requires user interaction. A target must open a specially crafted V-SFT file in the desktop V-SFT v6 editor. Because V-SFT is used by control engineers to design HMI screens for Monitouch panels, compromised engineering workstations can serve as a pivot into operational technology (OT) environments.

Root Cause

The root cause is missing or insufficient validation of size and offset fields read from untrusted V-SFT file content before the WinFontDynStrCheck routine copies data into a fixed-size buffer. The function trusts file-supplied length values and writes beyond allocated memory boundaries.

Attack Vector

The attack vector is local and requires user interaction. An attacker delivers a malicious V-SFT project file through email, removable media, or a shared engineering repository. When the target opens the file, the parser triggers the out-of-bounds write, enabling information disclosure, application crash, or arbitrary code execution under the privileges of the V-SFT user.

No public proof-of-concept exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Technical specifics of the corrupted memory layout have not been published. See the JVN Security Advisory for vendor-reviewed technical detail.

Detection Methods for CVE-2025-61857

Indicators of Compromise

Unexpected crashes or ABEND events in V-SFT.exe or modules loading VS6ComFile.dll
V-SFT project files received from untrusted sources or arriving via email attachments
Child processes spawned by V-SFT.exe outside normal engineering workflows, such as cmd.exe, powershell.exe, or rundll32.exe
Outbound network connections originating from the V-SFT process to non-corporate destinations

Detection Strategies

Monitor Windows Error Reporting (WER) and application crash logs for faults in VS6ComFile.dll referencing CItemExChange::WinFontDynStrCheck
Apply behavioral endpoint detection rules that flag process injection or anomalous child process creation from engineering software
Inspect file shares and email gateways for V-SFT project files originating outside the engineering team

Monitoring Recommendations

Enable detailed process and module load auditing on engineering workstations running V-SFT
Forward endpoint telemetry from OT engineering systems to a centralized SIEM for correlation
Track software inventory to identify V-SFT installations at version 6.2.7.0 or earlier across the environment

How to Mitigate CVE-2025-61857

Immediate Actions Required

Identify all hosts running V-SFT v6 and confirm installed version against 6.2.7.0
Restrict opening of V-SFT project files to those received from verified internal sources
Apply the vendor-supplied update from Fuji Electric as soon as it is available for your region
Isolate engineering workstations from general-purpose corporate networks where feasible

Patch Information

Fuji Electric distributes updated V-SFT v6 software through the Monitouch download portal. Administrators should download the fixed release referenced in the JVN Security Advisory and replace installations running 6.2.7.0 or earlier. Verify file integrity using vendor-published hashes before deployment.

Workarounds

Block V-SFT project file extensions at email gateways when senders are external
Run V-SFT under a standard user account rather than an administrator account to limit code execution impact
Apply application allowlisting to prevent unauthorized child processes from launching out of V-SFT.exe
Store engineering project files only on access-controlled internal repositories

bash

# Example: enumerate V-SFT installations across Windows engineering hosts
Get-WmiObject -Class Win32_Product | Where-Object {
    $_.Name -like "*V-SFT*"
} | Select-Object Name, Version, InstallDate