CVE-2025-66635 is a stack-based buffer overflow vulnerability identified in SEIKO EPSON CORPORATION's Web Config product, a web-based configuration interface commonly used for managing Epson devices. The vulnerability arises when a logged-in user with sufficient privileges submits specially crafted data input, which overflows a stack buffer and enables arbitrary code execution on the affected system. This type of vulnerability is critical because it can allow attackers to execute malicious code with the privileges of the Web Config process, potentially leading to full system compromise. The vulnerability requires network access (AV:N) and high privileges (PR:H), but no user interaction beyond authentication is needed (UI:N). The scope is unchanged (S:U), meaning the impact is limited to the vulnerable component. The CVSS v3.0 base score is 7.2, indicating a high severity level due to the combined impact on confidentiality, integrity, and availability (all high). Although no public exploits have been reported yet, the nature of the vulnerability makes it a significant risk once weaponized. The affected versions are not explicitly listed, so organizations must consult vendor advisories for precise version information and patches. The vulnerability is particularly concerning for environments where Epson Web Config is exposed to internal networks or where multiple users have administrative access. Attackers exploiting this flaw could gain control over devices or pivot within networks, potentially disrupting operations or exfiltrating sensitive data.

For European organizations, the impact of CVE-2025-66635 can be substantial, especially in sectors relying heavily on Epson devices managed via Web Config, such as manufacturing, healthcare, and public administration. Successful exploitation could lead to unauthorized code execution, allowing attackers to manipulate device configurations, disrupt services, or use compromised devices as footholds for lateral movement within corporate networks. This threatens the confidentiality of sensitive information, the integrity of device configurations, and the availability of critical services. Given the high privileges required, insider threats or compromised credentials could accelerate exploitation. Additionally, organizations with regulatory obligations under GDPR must consider the potential data breach implications. The absence of known exploits in the wild provides a window for proactive mitigation, but the high severity score underscores the urgency of addressing this vulnerability to prevent future attacks.

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 network segmentation and firewall rules limiting access to trusted administrators only. 3. Enforce strong authentication mechanisms and regularly audit user privileges to minimize the risk of credential compromise or misuse. 4. Monitor logs and network traffic for unusual activities related to Web Config, such as unexpected input patterns or unauthorized access attempts. 5. Consider deploying application-layer firewalls or intrusion prevention systems that can detect and block buffer overflow attack patterns targeting Web Config. 6. Educate administrators about the risks of this vulnerability and ensure they follow secure configuration and operational best practices. 7. If patching is delayed, temporarily disable or limit the use of Web Config interfaces where feasible to reduce exposure. 8. Maintain an incident response plan tailored to potential exploitation scenarios involving device management interfaces.