CVE-2026-1459 is an OS command injection vulnerability classified under CWE-78, affecting the Zyxel VMG3625-T50B firmware versions up to 5.50(ABPM.9.7)C0. The flaw resides in the TR-369 certificate download CGI program, which improperly neutralizes special elements in input parameters, allowing an authenticated attacker with administrator privileges to inject and execute arbitrary operating system commands on the device. This vulnerability requires no user interaction but does require high-level privileges, meaning the attacker must already have administrative access to the device's management interface. The CVSS v3.1 base score is 7.2, reflecting high severity due to the potential for complete compromise of the device's confidentiality, integrity, and availability. Exploiting this vulnerability could allow attackers to manipulate device configurations, disrupt network services, or pivot to other internal systems. Although no public exploits have been reported yet, the presence of this vulnerability in widely deployed network equipment poses a significant risk. The lack of available patches at the time of reporting necessitates immediate mitigation through access controls and monitoring. The vulnerability highlights the importance of secure input validation in embedded device management interfaces, especially those exposed to administrative users.

The impact of CVE-2026-1459 is substantial for organizations using the Zyxel VMG3625-T50B as a network gateway or router. Successful exploitation allows attackers with administrative credentials to execute arbitrary OS commands, potentially leading to full device compromise. This can result in unauthorized disclosure of sensitive network information, alteration or destruction of device configurations, denial of service through device instability or reboot, and the ability to launch further attacks within the internal network. Given the device’s role in managing network traffic and security, compromise could disrupt business operations, degrade network performance, and expose connected systems to additional threats. The requirement for administrative access limits the attack surface but does not eliminate risk, especially in environments with weak credential management or insider threats. The vulnerability could also be leveraged in targeted attacks against critical infrastructure or enterprises relying on this hardware, amplifying its potential impact.

Organizations should immediately audit and restrict administrative access to the Zyxel VMG3625-T50B devices, enforcing strong, unique passwords and multi-factor authentication where possible. Network segmentation should be employed to limit access to device management interfaces to trusted personnel and systems only. Monitoring and logging of administrative activities should be enhanced to detect suspicious command execution or configuration changes. Until a vendor patch is released, consider disabling or restricting the TR-369 certificate download CGI program if feasible. Regularly check Zyxel’s official channels for firmware updates addressing this vulnerability and apply them promptly once available. Additionally, conduct vulnerability assessments and penetration tests to identify any unauthorized access or exploitation attempts. Educate administrators on the risks of command injection vulnerabilities and the importance of secure device management practices. Implement network intrusion detection systems capable of identifying anomalous command injection patterns targeting network devices.