CVE-2025-8078 is an OS command injection vulnerability classified under CWE-78, discovered in multiple Zyxel device firmware versions, including ATP series (V4.32 through V5.40), USG FLEX series (V4.50 through V5.40), USG FLEX 50(W) series (V4.16 through V5.40), and USG20(W)-VPN series (V4.16 through V5.40). The vulnerability arises from improper neutralization of special elements in user-supplied input passed as arguments to command-line interface (CLI) commands. An attacker with authenticated administrator privileges can exploit this flaw by injecting crafted strings into CLI commands, leading to arbitrary OS command execution on the device. This can result in complete device compromise, including unauthorized data access, configuration manipulation, or denial of service. The vulnerability does not require user interaction beyond authentication but does require high privileges, limiting exploitation to insiders or attackers who have already compromised credentials. The CVSS v3.1 base score is 7.2, reflecting high impact on confidentiality, integrity, and availability, with network attack vector and low attack complexity. No public exploits or patches are currently available, but the vulnerability is publicly disclosed and should be considered critical for affected environments.

For European organizations, the impact of CVE-2025-8078 can be severe due to the widespread use of Zyxel ATP and USG series devices in enterprise and governmental networks for perimeter security and VPN access. Successful exploitation could allow attackers to gain full control over these security appliances, enabling interception or manipulation of network traffic, disruption of VPN services, and potential lateral movement within networks. This could lead to data breaches, operational downtime, and compromise of sensitive information. Critical infrastructure sectors such as energy, finance, and public administration that rely on Zyxel devices for secure communications are particularly vulnerable. The requirement for administrator credentials reduces the risk of external exploitation but raises concerns about insider threats and credential theft. The absence of known exploits in the wild provides a window for proactive mitigation, but the high severity score demands urgent attention to prevent potential targeted attacks.

European organizations should implement the following specific mitigations: 1) Immediately audit and restrict administrative access to Zyxel devices, enforcing strong multi-factor authentication and limiting access to trusted personnel only. 2) Monitor device logs and CLI command usage for unusual or unauthorized activity indicative of attempted command injection. 3) Apply network segmentation to isolate management interfaces from general network access, reducing exposure to potential attackers. 4) Regularly back up device configurations and firmware to enable rapid recovery if compromise occurs. 5) Stay informed on Zyxel’s security advisories and apply firmware updates promptly once patches for CVE-2025-8078 are released. 6) Consider deploying intrusion detection/prevention systems (IDS/IPS) tuned to detect anomalous command execution patterns on network security devices. 7) Conduct internal security awareness training emphasizing the risks of credential compromise and the importance of secure administrative practices. These targeted actions go beyond generic advice by focusing on access control, monitoring, and preparedness specific to the nature of this vulnerability.