CVE-2025-11296 is a high-severity remote buffer overflow vulnerability affecting the Belkin F9K1015 router, specifically version 1.00.10. The vulnerability exists in the handling of the /goform/formPPTPSetup endpoint, where improper validation of the 'pptpUserName' parameter allows an attacker to overflow a buffer. This flaw can be exploited remotely without authentication or user interaction, making it particularly dangerous. The buffer overflow can lead to arbitrary code execution with elevated privileges, potentially allowing attackers to take full control of the device. The vulnerability has a CVSS 4.0 base score of 8.7, reflecting its ease of exploitation (network attack vector, low attack complexity, no privileges or user interaction required) and its severe impact on confidentiality, integrity, and availability. Although the vendor was notified early, no patch or response has been issued, and while no known exploits are currently observed in the wild, public disclosure increases the risk of exploitation by threat actors. The affected device is a consumer and small office/home office (SOHO) router, which is often deployed in both residential and small business environments, making it a potential entry point for attackers targeting internal networks or leveraging the device for further lateral movement or persistent access.

For European organizations, especially small and medium enterprises (SMEs) and home office users relying on Belkin F9K1015 routers, this vulnerability poses a significant risk. Exploitation could lead to unauthorized network access, interception or manipulation of network traffic, and potential compromise of connected devices. Given the router’s role as a gateway, attackers could establish persistent footholds, exfiltrate sensitive data, or launch further attacks against internal resources. The lack of vendor response and patch availability increases the window of exposure. Critical infrastructure or organizations with remote workers using vulnerable devices may face increased risk of espionage, data breaches, or disruption of services. The vulnerability’s remote exploitability without authentication makes it a prime target for automated scanning and exploitation campaigns, potentially impacting confidentiality, integrity, and availability of organizational networks.

Immediate mitigation should focus on network-level controls and device isolation. Organizations should: 1) Identify and inventory all Belkin F9K1015 devices running firmware version 1.00.10. 2) Restrict remote management access to these devices by disabling WAN-side administration and limiting access to trusted IP addresses or VPNs. 3) Implement network segmentation to isolate vulnerable routers from critical assets. 4) Monitor network traffic for unusual activity targeting the /goform/formPPTPSetup endpoint or suspicious PPTP-related traffic. 5) If possible, replace affected devices with models from vendors providing timely security updates. 6) Employ intrusion detection/prevention systems (IDS/IPS) with signatures for known buffer overflow attempts against this router. 7) Regularly check for vendor updates or community patches and apply them promptly once available. 8) Educate users about the risks of using outdated router firmware and encourage secure configuration practices.