CVE-2025-61856 is a stack-based buffer overflow vulnerability identified in the VS6ComFile!CV7BaseMap::WriteV7DataToRom function of V-SFT software, versions 6.2.7.0 and earlier, developed by FUJI ELECTRIC CO., LTD. and Hakko Electronics Co., Ltd. V-SFT is used primarily for programming and managing industrial automation systems. The vulnerability arises when the software processes specially crafted V-SFT files, which can overflow a stack buffer due to insufficient bounds checking. This overflow can corrupt the stack, potentially allowing an attacker to execute arbitrary code, cause abnormal system termination (ABEND), or disclose sensitive information from memory. The CVSS 3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability. The attack vector is local (AV:L), requiring the victim to open a malicious file (UI:R), but no privileges are needed (PR:N). The vulnerability scope is unchanged (S:U), meaning it affects only the vulnerable component. No patches or known exploits are currently published, but the risk is significant given the potential for remote code execution if an attacker can trick a user into opening a malicious file. This vulnerability is particularly critical in industrial environments where V-SFT is used to configure programmable logic controllers (PLCs) and other control devices, as exploitation could disrupt critical infrastructure operations or lead to espionage.

For European organizations, especially those in manufacturing, energy, and critical infrastructure sectors relying on FUJI ELECTRIC's V-SFT software for industrial automation, this vulnerability poses a serious risk. Exploitation could lead to unauthorized disclosure of sensitive operational data, disruption of industrial processes through system crashes, or full system compromise via arbitrary code execution. Such impacts could result in operational downtime, safety hazards, financial losses, and damage to reputation. Given the local attack vector and requirement for user interaction, insider threats or targeted spear-phishing campaigns are plausible attack scenarios. The potential for cascading effects in interconnected industrial control systems elevates the risk to national critical infrastructure. Organizations in Europe with extensive industrial automation deployments must consider this vulnerability a priority for risk management and incident response planning.

Immediate mitigation steps include restricting access to V-SFT project files and ensuring only trusted personnel handle these files. Implement strict file validation and scanning policies to detect malformed V-SFT files before opening. Employ application whitelisting and sandboxing techniques to limit the impact of potential exploitation. Monitor systems running V-SFT for unusual behavior or crashes indicative of exploitation attempts. Since no patches are currently available, coordinate with FUJI ELECTRIC and Hakko Electronics for timely updates and advisories. Educate users about the risks of opening unsolicited or suspicious V-SFT files. For long-term mitigation, segment industrial networks to isolate V-SFT workstations from broader enterprise networks, reducing exposure. Maintain robust backup and recovery procedures to minimize downtime in case of successful exploitation.