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, across several 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, where improper handling of the vlan_set 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 with elevated privileges, potentially allowing full compromise of the device. The vendor, Linksys, has not responded to disclosure attempts, and no patches have been released at the time of publication. Although no known exploits are currently observed in the wild, the public disclosure of the exploit code increases the risk of imminent attacks. The CVSS 4.0 score of 8.7 reflects the vulnerability’s critical impact on confidentiality, integrity, and availability, combined with its ease of exploitation and lack of required privileges or user interaction.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and small-to-medium businesses relying on Linksys range extenders to improve wireless network coverage. Successful exploitation could allow attackers to gain control over network infrastructure devices, enabling interception or manipulation of network traffic, lateral movement within internal networks, and potential deployment of further malware or ransomware. This could lead to data breaches, disruption of business operations, and compromise of sensitive information. Given the remote exploitability and lack of vendor patching, attackers could rapidly weaponize this vulnerability. Critical infrastructure sectors, including finance, healthcare, and government entities in Europe, often use such network devices, increasing the potential impact. Additionally, home office environments, which have grown in prevalence, may also be vulnerable, potentially serving as entry points for attacks against corporate networks.

Immediate mitigation should focus on network segmentation to isolate vulnerable Linksys devices from critical internal networks. Organizations should disable remote management features on these devices to reduce exposure. Monitoring network traffic for unusual activity targeting the /goform/setVlan endpoint can help detect exploitation attempts. Since no official patches are available, organizations should consider replacing affected devices with models from vendors that provide timely security updates. Applying strict firewall rules to restrict access to the management interfaces of these devices is critical. Additionally, organizations should implement network intrusion detection systems (NIDS) with signatures tailored to detect attempts exploiting this specific buffer overflow. Regularly auditing network devices for vulnerable firmware versions and maintaining an asset inventory will aid in rapid identification and remediation. Finally, organizations should stay alert for vendor updates or third-party patches and apply them promptly once available.