CVE-2025-11294 is a high-severity buffer overflow vulnerability identified in the Belkin F9K1015 router, specifically in firmware version 1.00.10. The vulnerability arises from improper handling of the L2TPUserName argument within the /goform/formL2TPSetup endpoint. This endpoint is likely part of the router's web-based management interface that configures L2TP VPN settings. By sending a specially crafted request manipulating the L2TPUserName parameter, an attacker can trigger a buffer overflow condition. Buffer overflows occur when data exceeds the allocated buffer size, potentially overwriting adjacent memory and leading to arbitrary code execution or system crashes. The vulnerability can be exploited remotely over the network without requiring user interaction or prior authentication, as indicated by the CVSS vector (AV:N/AC:L/AT:N/UI:N/PR:L). The CVSS 4.0 base score of 8.7 reflects the high impact on confidentiality, integrity, and availability, with the potential for complete system compromise. The vendor, Belkin, was notified early but has not responded or issued a patch, and a public exploit is available, increasing the risk of exploitation. Although no known exploits in the wild have been reported yet, the public availability of the exploit code significantly raises the threat level. The vulnerability affects only firmware version 1.00.10 of the F9K1015 model, which is a consumer-grade router commonly used in small offices and home environments. The lack of authentication requirement and ease of exploitation make this a critical risk for networks relying on this device for VPN connectivity or general routing functions.

For European organizations, this vulnerability poses a significant risk, especially for small and medium enterprises (SMEs) and home offices that use the Belkin F9K1015 router. Successful exploitation could allow attackers to execute arbitrary code on the router, leading to full device compromise. This could result in interception or manipulation of network traffic, disruption of VPN services, and potential lateral movement into internal networks. Confidential data transmitted over the network could be exposed or altered, undermining data integrity and privacy compliance obligations under regulations such as GDPR. The availability of a public exploit increases the likelihood of automated scanning and attacks targeting vulnerable devices across Europe. Given the critical role of VPNs in securing remote work, exploitation could disrupt business continuity and expose sensitive communications. Additionally, compromised routers could be leveraged as part of botnets or for launching further attacks, amplifying the threat landscape for European networks.

Since the vendor has not released a patch, European organizations should take immediate compensating controls. First, identify and inventory all Belkin F9K1015 devices running firmware version 1.00.10 within the network. If possible, upgrade to a newer firmware version if available or replace the device with a more secure router model. If replacement is not immediately feasible, restrict access to the router's management interface by implementing network segmentation and firewall rules that limit access to trusted IP addresses only. Disable the L2TP VPN service or the vulnerable endpoint if it is not in use. Monitor network traffic for unusual activity or attempts to access /goform/formL2TPSetup. Employ intrusion detection/prevention systems (IDS/IPS) with signatures targeting this exploit. Additionally, consider deploying network-level anomaly detection to identify exploitation attempts. Maintain up-to-date backups of router configurations and network devices to enable rapid recovery. Finally, stay informed about any vendor updates or security advisories and apply patches promptly once available.