CVE-2026-0839 identifies a buffer overflow vulnerability in the UTT 进取 520W wireless router firmware version 1.7.7-180627. The vulnerability arises from improper handling of the 'wepkey1' parameter in the /goform/APSecurity endpoint, where the strcpy function copies input data without bounds checking. This allows an attacker to send a specially crafted request remotely to overflow the buffer, potentially overwriting adjacent memory and enabling arbitrary code execution or causing a denial of service. The vulnerability requires no authentication or user interaction, making it highly exploitable over the network. The CVSS 4.0 score of 8.7 reflects its critical impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. Although the vendor was notified early, no patch or response has been provided, and a public exploit is available, increasing the likelihood of active exploitation. This vulnerability affects a specific firmware version, so devices running 1.7.7-180627 are at risk. The lack of vendor response and public exploit availability necessitate immediate defensive measures to prevent compromise.

For European organizations, this vulnerability poses a significant risk due to the potential for remote code execution and denial of service on affected routers. Compromise of these devices can lead to network infiltration, data exfiltration, disruption of services, and lateral movement within corporate or critical infrastructure networks. Organizations relying on UTT 进取 520W routers, especially in sectors like telecommunications, government, energy, and manufacturing, may face operational disruptions and data breaches. The absence of a vendor patch increases exposure time, and the availability of a public exploit lowers the barrier for attackers, including cybercriminals and nation-state actors. This could lead to targeted attacks against European entities or widespread opportunistic exploitation. Additionally, compromised routers could be used as entry points for broader attacks or as part of botnets, amplifying the threat landscape.

Given the absence of an official patch, European organizations should implement immediate network-level mitigations. These include isolating affected devices from untrusted networks, restricting access to the /goform/APSecurity endpoint via firewall rules or network segmentation, and disabling remote management interfaces if not required. Monitoring network traffic for anomalous requests targeting the 'wepkey1' parameter can help detect exploitation attempts. Organizations should inventory their network devices to identify any running the vulnerable firmware version and prioritize their replacement or upgrade once a patch is available. Employing intrusion detection/prevention systems (IDS/IPS) with signatures for this exploit can provide additional defense. Finally, organizations should engage with UTT or authorized vendors to seek firmware updates or guidance and consider alternative hardware if remediation is delayed.