CVE-2025-8819 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 setWan function within the /goform/setWan endpoint, where improper handling of the 'staticIp' argument allows an attacker to overflow the stack buffer. This flaw can be exploited remotely without requiring user interaction or prior authentication, as indicated by the CVSS vector (AV:N/AC:L/AT:N/UI:N/PR:L). The vulnerability impacts confidentiality, integrity, and availability with high impact, enabling potential remote code execution or denial of service. Although the vendor was notified early, no response or patch has been issued, and public exploit code has been disclosed, increasing the risk of exploitation. The vulnerability's exploitation requires only low privileges (PR:L), which may correspond to limited access or a low-level authenticated user, but no user interaction is needed. The absence of vendor patches and public exploit availability makes this a critical concern for affected devices. The vulnerability's technical root cause is a classic stack buffer overflow triggered by improper input validation or bounds checking on the staticIp parameter, leading to memory corruption and potential arbitrary code execution or system crashes.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and service providers using Linksys range extenders in their network infrastructure. Exploitation could lead to unauthorized remote code execution, allowing attackers to gain control over network devices, intercept or manipulate network traffic, and disrupt network availability. This could compromise sensitive data confidentiality and integrity, particularly in environments relying on these devices for extending wireless coverage in offices or branch locations. The lack of vendor response and patches increases the window of exposure, making it likely that attackers will develop and deploy exploits targeting these devices. Additionally, compromised extenders could serve as pivot points for lateral movement within corporate networks or as part of botnets for broader attacks. The impact extends to critical infrastructure sectors that depend on reliable network connectivity, potentially affecting operational continuity and regulatory compliance under GDPR and other data protection frameworks.

Given the absence of official patches, European organizations should immediately audit their networks to identify the presence of affected Linksys models and firmware versions. Mitigation steps include: 1) Isolate or segment affected devices from critical network segments to limit potential lateral movement. 2) Disable remote management interfaces or restrict access to trusted IP addresses only. 3) Replace vulnerable devices with updated hardware from vendors with active security support if possible. 4) Implement network-level intrusion detection/prevention systems (IDS/IPS) with signatures targeting known exploit patterns for this vulnerability. 5) Monitor network traffic for unusual activity or attempts to access the /goform/setWan endpoint. 6) Enforce strict network access controls and multi-factor authentication for device management interfaces to reduce privilege escalation risks. 7) Engage with Linksys or authorized resellers to demand timely security updates and consider alternative vendors with better security track records. 8) Maintain up-to-date asset inventories and vulnerability management processes to quickly respond to emerging threats.