CVE-2025-9247 is a high-severity stack-based buffer overflow vulnerability affecting multiple Linksys range extender models, including RE6250, RE6300, RE6350, RE6500, RE7000, and RE9000, specifically in firmware versions 1.0.013.001, 1.0.04.001, 1.0.04.002, 1.1.05.003, and 1.2.07.001. The vulnerability resides in the setVlan function within the /goform/setVlan endpoint. An attacker can remotely manipulate the vlan_set argument to trigger a stack-based buffer overflow, potentially allowing arbitrary code execution or denial of service. The vulnerability is remotely exploitable without 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 is 8.7, reflecting high impact on confidentiality, integrity, and availability with low attack complexity. Although the vendor was notified early, no response or patch has been released, and public exploit code has been disclosed, increasing the risk of exploitation. The vulnerability affects critical network infrastructure devices that extend wireless network coverage, which are often deployed in both home and enterprise environments. The lack of patch availability combined with public exploit disclosure elevates the urgency for mitigation and risk management.

For European organizations, this vulnerability poses significant risks to network security and operational continuity. Linksys range extenders are widely used to improve wireless coverage in offices, retail locations, and industrial sites. Exploitation could allow attackers to execute arbitrary code on these devices, leading to network compromise, interception or manipulation of traffic, lateral movement within internal networks, or complete denial of service of network extension capabilities. This can disrupt business operations, degrade service availability, and expose sensitive data. The remote and unauthenticated nature of the exploit increases the attack surface, especially for organizations with exposed or poorly segmented network infrastructure. Given the public availability of exploit code and the absence of vendor patches, European entities face an elevated threat level, particularly those relying on vulnerable Linksys models in critical environments. The impact extends beyond confidentiality breaches to include integrity and availability concerns, potentially affecting compliance with data protection regulations such as GDPR if personal data is compromised or service interruptions occur.

Immediate mitigation steps should include: 1) Inventory and identify all Linksys range extenders in use, focusing on the affected models and firmware versions. 2) Isolate vulnerable devices from direct internet exposure by implementing network segmentation and firewall rules restricting access to management interfaces, especially the /goform/setVlan endpoint. 3) Disable remote management features if not strictly necessary to reduce attack vectors. 4) Monitor network traffic for unusual requests targeting the vlan_set parameter or signs of exploitation attempts. 5) Employ intrusion detection/prevention systems (IDS/IPS) with updated signatures to detect exploitation attempts. 6) Engage with Linksys support channels persistently to demand patch releases or official guidance. 7) Consider replacing vulnerable devices with alternatives from vendors providing timely security updates if patches remain unavailable. 8) Implement compensating controls such as VPN access for management and strict authentication mechanisms to reduce unauthorized access risk. 9) Regularly review and update network security policies to incorporate lessons learned from this vulnerability. These targeted actions go beyond generic advice by focusing on device-specific controls and proactive network defense measures.