CVE-2025-11296 is a buffer overflow vulnerability identified in the Belkin F9K1015 router firmware version 1.00.10. The flaw exists in the handling of the pptpUserName parameter within the /goform/formPPTPSetup endpoint, which is part of the router's web management interface. An attacker can remotely send a specially crafted request manipulating this parameter to overflow a buffer, potentially overwriting adjacent memory. This can lead to arbitrary code execution or denial of service conditions. The vulnerability requires no authentication and no user interaction, making it highly exploitable over the network. The CVSS 4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with low attack complexity and no privileges required. The vendor was notified but has not issued any patch or mitigation guidance, and while no active exploits are reported in the wild, the public disclosure of exploit code increases the risk of imminent attacks. The affected device is commonly used in small office and home office environments, which may be part of larger corporate networks, increasing the potential attack surface.

For European organizations, the impact of this vulnerability can be significant. Exploitation could allow attackers to gain unauthorized access to internal networks by compromising perimeter routers, leading to data breaches, network disruption, or lateral movement within corporate environments. Confidentiality is at risk due to potential interception or manipulation of network traffic. Integrity could be compromised if attackers alter configurations or inject malicious payloads. Availability may be affected if the router crashes or is rendered inoperable. Given the lack of vendor response and patches, organizations face prolonged exposure. This is particularly critical for sectors relying on secure and stable network infrastructure, such as finance, healthcare, and government. The vulnerability also poses risks to home offices and remote workers using this device, potentially serving as entry points into corporate networks.

Immediate mitigation should include isolating affected Belkin F9K1015 devices from untrusted networks and disabling the PPTP setup functionality if possible. Network segmentation should be enforced to limit access to router management interfaces. Employ strict firewall rules to restrict inbound traffic to trusted sources only. Monitoring network traffic for unusual requests targeting /goform/formPPTPSetup can help detect exploitation attempts. Organizations should consider replacing vulnerable devices with models from vendors that provide timely security updates. If replacement is not feasible, deploying compensating controls such as VPNs and intrusion detection/prevention systems can reduce risk. Regularly audit network devices for firmware versions and ensure all other devices are updated. Engage with Belkin support channels to seek official patches or guidance and track vulnerability disclosures for updates.