CVE-2025-11299 is a high-severity buffer overflow vulnerability found in the Belkin F9K1015 router, specifically in version 1.00.10 of its firmware. The vulnerability resides in an unspecified function within the /goform/formWanTcpipSetup endpoint, where improper handling of the pppUserName argument allows an attacker to overflow a buffer. This flaw can be exploited remotely without requiring user interaction or prior authentication, making it particularly dangerous. The vulnerability has a CVSS 4.0 base score of 8.7, reflecting its high impact on confidentiality, integrity, and availability. The exploit is publicly available, increasing the risk of exploitation, although no active exploitation in the wild has been reported yet. The vendor, Belkin, has been contacted but has not responded or issued a patch, leaving affected devices exposed. The vulnerability allows an attacker to potentially execute arbitrary code or cause a denial of service, compromising the router's operation and potentially the entire network it protects. Given the router's role as a network gateway device, successful exploitation could lead to network traffic interception, manipulation, or disruption, severely impacting organizational security.

For European organizations using the Belkin F9K1015 router, this vulnerability poses a significant risk. Exploitation could lead to unauthorized access to internal networks, data interception, or disruption of internet connectivity. This is especially critical for small and medium enterprises (SMEs) and home office environments that rely on this router model for their primary internet access without advanced security monitoring. The compromise of these routers could facilitate lateral movement within corporate networks or serve as a foothold for further attacks. Additionally, critical infrastructure or organizations in sectors such as finance, healthcare, or government using these devices could face operational disruptions or data breaches. The lack of vendor response and patch availability exacerbates the risk, as organizations must rely on mitigations or device replacement to protect themselves.

Given the absence of an official patch, European organizations should take immediate steps to mitigate this vulnerability. First, identify and inventory all Belkin F9K1015 devices running firmware version 1.00.10. Where possible, replace these routers with models from vendors with active security support. If replacement is not immediately feasible, restrict remote access to the router's management interface by implementing network-level access controls such as firewall rules limiting access to trusted IP addresses only. Disable any unnecessary remote management features to reduce the attack surface. Monitor network traffic for unusual activity that could indicate exploitation attempts. Employ intrusion detection/prevention systems (IDS/IPS) with signatures for known exploits targeting this vulnerability. Regularly review vendor communications for any updates or patches. Finally, educate IT staff about this vulnerability and ensure incident response plans include steps for potential exploitation scenarios involving network infrastructure devices.