CVE-2025-8817 is a high-severity stack-based buffer overflow vulnerability affecting multiple Linksys range extender models, including RE6250, RE6300, RE6350, RE6500, RE7000, and RE9000, up to firmware version 20250801. The vulnerability resides in the setLan function within the /goform/setLan endpoint, where improper handling of the 'lan2enabled' argument allows an attacker to overflow a stack buffer. This overflow can be triggered remotely without authentication or user interaction, enabling an attacker to execute arbitrary code or cause a denial of service on the affected device. The vulnerability has been publicly disclosed, and while no known exploits are currently observed in the wild, the availability of a public exploit increases the risk of exploitation. The vendor, Linksys, has not responded to early disclosure attempts, and no patches or mitigations have been officially released at this time. The CVSS v4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, combined with the ease of remote exploitation without privileges or user interaction. This vulnerability poses a significant threat to network security, as compromised range extenders can be used as footholds for lateral movement, data interception, or launching further attacks within corporate or home networks.

For European organizations, this vulnerability presents a critical risk to network infrastructure security. Linksys range extenders are commonly used in both enterprise branch offices and home office environments to extend Wi-Fi coverage. Exploitation could lead to unauthorized remote code execution, allowing attackers to intercept or manipulate network traffic, disrupt connectivity, or pivot to more sensitive internal systems. Given the remote and unauthenticated nature of the exploit, attackers can target exposed devices directly from the internet or compromised internal hosts. This could result in data breaches, operational disruptions, and potential compromise of connected devices. The lack of vendor response and patches increases the window of exposure, making timely mitigation essential. Organizations relying on these devices for network extension or segmentation should consider the risk of persistent compromise and potential regulatory implications under GDPR if personal data is exposed or network integrity is compromised.

1. Immediate network segmentation: Isolate affected Linksys range extenders from critical network segments to limit potential lateral movement. 2. Disable remote management interfaces on these devices to reduce exposure to external attackers. 3. Monitor network traffic for unusual patterns or signs of exploitation attempts targeting /goform/setLan or abnormal LAN2 configuration changes. 4. Replace vulnerable devices with alternative hardware from vendors with active security support if patching is unavailable. 5. If replacement is not immediately feasible, consider deploying firewall rules to block access to the vulnerable endpoint and restrict management access to trusted internal IPs only. 6. Maintain up-to-date asset inventories to identify all affected devices and prioritize remediation efforts. 7. Engage with Linksys support channels regularly for updates or patches, and consider reporting the lack of response to relevant cybersecurity authorities or CERTs to increase pressure for a fix. 8. Educate IT staff about this vulnerability and incorporate it into incident response plans to ensure rapid detection and containment if exploitation occurs.