CVE-2025-54526: Monitouch V-SFT Buffer Overflow Flaw

CVE-2025-54526 Overview

CVE-2025-54526 is a stack-based buffer overflow [CWE-121] in Fuji Electric Monitouch V-SFT-6, a configuration and screen design tool used with Monitouch human-machine interface (HMI) products in industrial control environments. The vulnerability is triggered when the application processes a specially crafted project file. An attacker who convinces an engineer or operator to open a malicious project file can execute arbitrary code in the context of the V-SFT-6 process.

The issue was published to the National Vulnerability Database (NVD) on November 4, 2025 and is tracked under CISA ICS Advisory ICSA-25-308-01.

Critical Impact
Successful exploitation allows arbitrary code execution on engineering workstations used to configure operational technology (OT) HMI devices, providing a pivot point into industrial control system (ICS) environments.

Affected Products

Fuji Electric Monitouch V-SFT-6 (all versions prior to the vendor-released fix)
V-SFT software family used to design Monitouch HMI projects
Engineering workstations running V-SFT-6 in OT environments

Discovery Timeline

2025-11-04 - CVE-2025-54526 published to NVD and disclosed via CISA ICS Advisory ICSA-25-308-01
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-54526

Vulnerability Analysis

The vulnerability is a stack-based buffer overflow in the V-SFT-6 project file parser. When V-SFT-6 loads a project file, untrusted data from the file is copied into a fixed-size stack buffer without sufficient bounds validation. An oversized or malformed field overruns the buffer and overwrites adjacent stack memory, including the saved return address and structured exception handler records on Windows.

Exploitation requires user interaction: a target user must open the malicious project file in V-SFT-6. The attack vector is local, but project files are commonly shared by email, removable media, vendor support channels, and shared engineering repositories, making delivery practical in OT settings.

Root Cause

The root cause is missing or incorrect length validation when parsing structured fields inside the proprietary V-SFT project file format. The parser trusts size or offset values declared in the file and copies attacker-controlled bytes onto the stack using an unbounded copy operation. This pattern is characteristic of [CWE-121: Stack-based Buffer Overflow].

Attack Vector

An attacker crafts a malicious V-SFT project file containing oversized parser fields and shellcode. The file is delivered to an engineer through phishing, a compromised vendor package, or shared project storage. When the engineer opens the file, V-SFT-6 parses the malformed structure, the stack buffer overruns, control flow is hijacked, and the attacker's payload executes with the privileges of the V-SFT-6 process. From that workstation, an adversary can stage further attacks against connected programmable logic controllers (PLCs) and HMIs.

No public proof-of-concept exploit is available at this time, and the issue is not listed on the CISA Known Exploited Vulnerabilities catalog. EPSS data places exploitation probability low as of June 2026.

Detection Methods for CVE-2025-54526

Indicators of Compromise

Unexpected child processes spawned by V-SFT.exe or related V-SFT-6 binaries, especially command interpreters such as cmd.exe, powershell.exe, or rundll32.exe
V-SFT-6 process crashes with access violations referencing corrupted stack frames or non-image return addresses
V-SFT project files (.V8, .V9, and related extensions) arriving from external email, USB media, or untrusted shares immediately before anomalous activity on the engineering workstation
Outbound network connections originating from V-SFT.exe to non-corporate destinations

Detection Strategies

Monitor process creation events on engineering workstations and alert on V-SFT-6 spawning interactive shells, scripting engines, or LOLBins
Apply Windows Defender Exploit Guard or equivalent attack surface reduction rules to block child process creation from V-SFT-6
Use file integrity monitoring to track project files arriving on engineering hosts and correlate opens with subsequent process behavior
Hunt for unsigned modules loaded into the V-SFT-6 process space

Monitoring Recommendations

Collect endpoint telemetry from OT engineering workstations into a centralized data lake or SIEM for behavioral analysis
Enable Windows Event Log channels for process creation (Event ID 4688) with command-line auditing on all hosts running V-SFT-6
Track network egress from segmented OT engineering subnets and alert on flows not matching documented vendor update destinations
Review crash dumps from V-SFT-6 for signatures of stack corruption and report them to Fuji Electric support

How to Mitigate CVE-2025-54526

Immediate Actions Required

Inventory all engineering workstations running Fuji Electric Monitouch V-SFT-6 and identify their installed versions
Apply the patched V-SFT-6 release from Fuji Electric as referenced in the CISA ICS Advisory ICSA-25-308-01
Restrict opening of V-SFT project files to those received through verified channels and validated against known-good sources
Isolate engineering workstations from general corporate networks and the internet, following ISA/IEC 62443 zone and conduit guidance

Patch Information

Fuji Electric has published updated V-SFT-6 software through its official software portal. Refer to the Fuji Electric Software Document Search and the CISA ICS Advisory ICSA-25-308-01 for fixed version details. The structured advisory data is also available as a CSAF document on GitHub.

Workarounds

Run V-SFT-6 only on dedicated engineering workstations that are not used for email or general web browsing
Open untrusted V-SFT project files only inside isolated virtual machines with no network access to OT assets
Enforce application allowlisting so that processes spawned by V-SFT-6 are limited to expected child binaries
Train engineering staff to verify the provenance of project files before opening them, especially files received from external integrators

bash

# Example: enable Windows audit policy for process creation with command line
auditpol /set /subcategory:"Process Creation" /success:enable /failure:enable
reg add "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\Audit" /v ProcessCreationIncludeCmdLine_Enabled /t REG_DWORD /d 1 /f