CVE-2025-6151 is a high-severity remote buffer overflow vulnerability affecting TP-Link Systems INC. routers, specifically the TL-WR940N V4 and TL-WR841N V11 models. The vulnerability resides in an unspecified functionality within the /userRpm/WanSlaacCfgRpm.htm file. It is caused by improper handling of input data leading to a classic buffer overflow (CWE-120), where the size of the input is not properly checked before copying it into a buffer. This flaw can be exploited remotely without user interaction or authentication, as indicated by the CVSS vector (AV:N/AC:L/AT:N/UI:N/PR:H). The vulnerability impacts confidentiality, integrity, and availability, with a CVSS v4.0 score of 8.2, reflecting its high severity. Exploitation could allow an attacker with high privileges (PR:H) to execute arbitrary code or cause denial of service on the affected device. However, the affected products are no longer supported by the vendor, and no patches are currently available. There are no known exploits in the wild at the time of publication. The vulnerability is linked to classic buffer overflow weaknesses (CWE-120 and CWE-119), which are well-known and often lead to critical security breaches if exploited successfully.

For European organizations, the impact of this vulnerability could be significant, especially for those still using legacy TP-Link TL-WR940N V4 or TL-WR841N V11 routers in their network infrastructure. Successful exploitation could lead to remote code execution or denial of service, potentially allowing attackers to disrupt network connectivity, intercept or manipulate network traffic, or pivot into internal networks. This could compromise sensitive data confidentiality and integrity, disrupt business operations, and lead to regulatory compliance issues under GDPR if personal data is affected. The lack of vendor support and patches increases the risk, as organizations cannot rely on official fixes and must consider alternative mitigation strategies. The vulnerability's remote exploitability without user interaction makes it particularly dangerous in environments where these devices are exposed to untrusted networks or the internet.

Given that the affected devices are no longer supported and no patches are available, European organizations should prioritize the following mitigations: 1) Immediate replacement of affected TP-Link TL-WR940N V4 and TL-WR841N V11 routers with supported, updated models that receive security patches. 2) If replacement is not immediately feasible, isolate these devices from untrusted networks by placing them behind firewalls or restricting management interfaces to trusted internal networks only. 3) Disable or restrict access to the vulnerable /userRpm/WanSlaacCfgRpm.htm functionality if possible, through device configuration or network controls. 4) Monitor network traffic for unusual activity or signs of exploitation attempts targeting these devices. 5) Implement network segmentation to limit the potential impact of a compromised router on critical systems. 6) Maintain an inventory of network devices to identify and track unsupported hardware and plan for timely upgrades. 7) Educate IT staff about the risks of unsupported devices and the importance of timely hardware lifecycle management.