CVE-2025-9778 is a security vulnerability identified in the Tenda W12 router models up to firmware version 3.0.0.6(3948). The vulnerability stems from hard-coded credentials embedded within the administrative interface, specifically related to an unknown function interacting with the /etc_ro/shadow file. This file typically stores password hashes or authentication data, and the presence of hard-coded credentials implies that an attacker with local access could potentially bypass normal authentication mechanisms. The attack vector requires local access to the device, meaning the attacker must be physically present or have access to the local network segment where the device resides. The complexity of exploiting this vulnerability is considered high, and the exploitability is difficult, indicating that successful exploitation would require significant effort or expertise. No user interaction is needed, and the vulnerability does not affect confidentiality, integrity, or availability beyond the local scope. The CVSS 4.0 base score is 1.8, categorized as low severity, reflecting the limited impact and challenging exploitation conditions. No known exploits are currently active in the wild, and no patches or mitigations have been officially published at this time. The vulnerability affects multiple firmware versions, from 1.0.0.1(5411) through 3.0.0.6(3948), indicating a broad range of devices may be impacted if not updated or mitigated.

For European organizations, the impact of CVE-2025-9778 is relatively limited due to the requirement for local access and the high complexity of exploitation. However, if an attacker gains physical or local network access, they could leverage the hard-coded credentials to gain administrative control over the Tenda W12 router. This could lead to unauthorized configuration changes, potential network traffic interception, or pivoting to other internal systems. Organizations relying on Tenda W12 devices in sensitive environments or with lax physical security controls could face increased risk. The vulnerability does not directly compromise confidentiality, integrity, or availability on a broad scale but could serve as a foothold for further attacks within a compromised network segment. Given the low CVSS score and absence of known exploits in the wild, the immediate risk is low, but the presence of hard-coded credentials is a poor security practice that should be addressed to prevent future exploitation.

To mitigate CVE-2025-9778, European organizations should first inventory their network infrastructure to identify any Tenda W12 devices running affected firmware versions. Since no official patches have been published, organizations should consider the following specific actions: 1) Restrict physical and local network access to Tenda W12 devices to trusted personnel only, employing network segmentation and access control lists to limit exposure. 2) Replace affected devices with models from vendors that do not have known hard-coded credential issues or that provide timely security updates. 3) Monitor network traffic for unusual administrative access attempts or configuration changes on Tenda W12 devices. 4) If possible, disable remote administrative interfaces and limit administrative access to wired connections rather than wireless. 5) Engage with Tenda support or vendor channels to request firmware updates or security advisories addressing this vulnerability. 6) Implement compensating controls such as network-level authentication and VPNs to restrict access to device management interfaces. These steps go beyond generic advice by focusing on device-specific controls and operational security measures tailored to the nature of the vulnerability.