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, specifically those running firmware versions up to 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 the stack buffer. This flaw can be exploited remotely without requiring user interaction or prior authentication, making it highly accessible to attackers. The buffer overflow can lead to arbitrary code execution, potentially allowing attackers to take full control of the affected device, disrupt network operations, or pivot into internal networks. The vulnerability has been publicly disclosed, and although 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 as of the publication date. The CVSS 4.0 base score of 8.7 reflects the critical nature of this vulnerability, with high impact on confidentiality, integrity, and availability, combined with low attack complexity and no required privileges or user interaction.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and service providers relying on Linksys range extenders to expand wireless network coverage. Successful exploitation could lead to complete compromise of the affected devices, enabling attackers to intercept or manipulate network traffic, disrupt connectivity, or use the compromised devices as footholds for further attacks within corporate or critical infrastructure networks. This is particularly concerning for sectors with stringent data protection requirements under GDPR, as unauthorized access or data leakage could result in regulatory penalties and reputational damage. Additionally, the lack of vendor response and patches increases the window of exposure. Organizations with remote or distributed network environments that utilize these Linksys models are at heightened risk, as attackers can exploit the vulnerability remotely without authentication or user interaction, facilitating large-scale automated attacks or targeted intrusions.

Given the absence of official patches, European organizations should immediately conduct comprehensive inventories to identify the presence of affected Linksys range extender models and firmware versions. Where possible, affected devices should be isolated from critical network segments or replaced with alternative hardware not vulnerable to this issue. Network segmentation should be enforced to limit access to management interfaces like /goform/setLan, ideally restricting them to trusted internal networks and blocking remote access via firewall rules. Intrusion detection and prevention systems should be configured to monitor and block suspicious HTTP requests targeting the setLan endpoint, especially those manipulating the 'lan2enabled' parameter. Organizations should also implement strict network monitoring to detect anomalous device behavior indicative of exploitation attempts. As a temporary workaround, disabling remote management features on these devices can reduce exposure. Finally, organizations should maintain close monitoring of vendor communications for any forthcoming patches and apply them promptly once available.