CVE-2025-3577 is a path traversal vulnerability identified in the Zyxel AMG1302-T10B firmware version 2.00(AAJC.16)C0. This vulnerability exists within the web management interface of the device, which is used for administrative configuration and monitoring. The flaw arises from improper limitation of pathname inputs (CWE-22), allowing an authenticated attacker with administrator privileges to craft specific HTTP requests that bypass directory restrictions. By exploiting this, the attacker can access files and directories outside the intended scope of the web interface, potentially exposing sensitive configuration files, logs, or other critical system data. The vulnerability requires prior authentication with administrative rights, which limits the initial attack surface but still poses a significant risk if credentials are compromised or if an insider threat exists. No public exploits have been reported in the wild to date, and Zyxel has not yet released a patch or mitigation guidance. The vulnerability was reserved and published in April 2025, indicating it is a recent discovery. Given the nature of the device—a broadband gateway commonly deployed in residential and small business environments—the impact could extend to network security and privacy if exploited. The vulnerability does not directly allow remote code execution but could facilitate further attacks by revealing sensitive information or configuration details that weaken the device's security posture.

For European organizations, especially small and medium enterprises (SMEs) and residential users relying on Zyxel AMG1302-T10B devices, this vulnerability could lead to unauthorized disclosure of sensitive network configuration data, including credentials, routing information, or VPN configurations. Such exposure could enable lateral movement within networks or facilitate man-in-the-middle attacks. Critical infrastructure operators or service providers using these devices as part of their network edge could face increased risk of targeted attacks. Although exploitation requires administrative authentication, credential theft or reuse from other breaches could enable attackers to leverage this vulnerability. The potential impact includes loss of confidentiality and integrity of network configurations, leading to degraded network security and possible service disruptions. Given the medium severity rating and lack of known exploits, the immediate risk is moderate, but the vulnerability could become more dangerous if combined with other attack vectors. The availability of the device is unlikely to be directly affected, but indirect impacts through compromised configurations could occur.

1. Immediate mitigation should focus on securing administrative access: enforce strong, unique passwords for device administrators and disable remote management interfaces if not required. 2. Implement network segmentation to isolate devices running vulnerable firmware from critical network assets, limiting potential lateral movement. 3. Monitor network traffic for unusual HTTP requests targeting the management interface that could indicate exploitation attempts. 4. Restrict access to the web management interface to trusted IP addresses or VPN-only access to reduce exposure. 5. Regularly audit and rotate administrative credentials to minimize the risk of credential compromise. 6. Engage with Zyxel support channels to obtain information on forthcoming patches or firmware updates addressing this vulnerability. 7. Consider deploying intrusion detection/prevention systems (IDS/IPS) with custom signatures to detect path traversal attempts against Zyxel devices. 8. For organizations with large deployments, conduct an inventory of affected devices and prioritize patching or replacement once updates become available. These steps go beyond generic advice by focusing on access control hardening, network isolation, and proactive monitoring tailored to the specific vulnerability context.