CVE-2025-66635 is a stack-based buffer overflow vulnerability identified in SEIKO EPSON CORPORATION's Web Config software, a tool commonly used for configuring Epson networked devices such as printers and multifunction peripherals. The vulnerability arises when a logged-in user submits specially crafted input data that exceeds the buffer limits on the stack, leading to memory corruption. This corruption can be exploited to execute arbitrary code with the privileges of the Web Config process. According to the CVSS 3.0 vector (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H) and a score of 7.2, the attack requires network access and authenticated user privileges but no user interaction beyond that. The vulnerability impacts confidentiality, integrity, and availability, as arbitrary code execution could lead to data theft, device manipulation, or denial of service. The affected product versions are not explicitly listed here, necessitating consultation of vendor advisories for precise version information. No known exploits have been reported in the wild yet, but the public disclosure increases the risk of exploitation attempts. The vulnerability is particularly concerning for environments where Epson Web Config is exposed to internal networks or where user credentials might be compromised. Attackers gaining code execution could pivot within networks or disrupt critical printing and document workflows. The stack-based buffer overflow nature suggests that exploitation could be reliable and potentially automated once exploit code is developed. This vulnerability highlights the importance of strict access controls and timely patching in device management software.

For European organizations, the impact of CVE-2025-66635 can be significant, especially in sectors relying heavily on Epson networked devices for document management, such as government agencies, financial institutions, healthcare providers, and large enterprises. Successful exploitation could lead to unauthorized access to sensitive documents, disruption of printing services, and potential lateral movement within corporate networks. This could result in data breaches, operational downtime, and reputational damage. Given that the vulnerability requires authenticated access, insider threats or compromised credentials pose a notable risk. The high severity score reflects the broad impact on confidentiality, integrity, and availability. Organizations with exposed or poorly segmented internal networks may face elevated risks. Additionally, critical infrastructure entities using Epson Web Config for device management could experience service interruptions or targeted attacks aiming to disrupt operations. The absence of known exploits in the wild currently provides a window for proactive mitigation, but the public disclosure necessitates urgent attention to prevent future exploitation. Overall, the vulnerability could facilitate advanced persistent threats or ransomware campaigns if leveraged as an initial foothold or escalation vector.

1. Immediately consult SEIKO EPSON CORPORATION's official advisories to identify affected versions and apply vendor-provided patches or updates as soon as they become available. 2. Restrict network access to the Web Config interface by implementing strict firewall rules and network segmentation, limiting access only to trusted administrators and management systems. 3. Enforce strong authentication mechanisms, including multi-factor authentication (MFA), to reduce the risk of credential compromise for users with access to Web Config. 4. Monitor logs and network traffic for unusual activities related to Web Config access, such as unexpected input patterns or privilege escalations. 5. Conduct regular vulnerability assessments and penetration testing focusing on device management interfaces to identify potential weaknesses. 6. Educate administrators about the risks of buffer overflow vulnerabilities and the importance of cautious input handling. 7. If patching is delayed, consider temporarily disabling or isolating the Web Config service to minimize exposure. 8. Implement endpoint detection and response (EDR) solutions to detect potential exploitation attempts and respond promptly. 9. Maintain an inventory of Epson devices and their firmware/software versions to prioritize remediation efforts. 10. Coordinate with Epson support for guidance on secure configurations and updates.