CVE-2025-57685 is a critical security vulnerability affecting multiple models of LB-Link routers, including BL-AC2100_AZ3 V1.0.4, BL-WR4000 v2.5.0, BL-WR9000_AE4 v2.4.9, BL-AC1900_AZ2 v1.0.2, BL-X26_AC8 v1.2.8, and BL-LTE300_DA4 V1.2.3. The vulnerability arises from an unauthorized command injection flaw accessible via the /goform/set_serial_cfg interface. This interface allows attackers to execute arbitrary commands on the device without any authentication, effectively granting them the highest privilege level on the router. Exploitation of this vulnerability enables remote attackers to take full control of the device, potentially allowing them to manipulate network traffic, install persistent malware, disrupt network availability, or pivot to other internal systems. The lack of authentication and the ability to execute commands remotely make this vulnerability particularly severe. Although no CVSS score has been assigned yet and no known exploits are reported in the wild, the technical details indicate a high risk due to the direct command injection vector and privilege escalation. The affected devices are widely used consumer and small business routers, which often serve as the primary gateway to internal networks, increasing the potential impact of compromise.

For European organizations, the exploitation of CVE-2025-57685 could have significant consequences. Many small and medium enterprises (SMEs) and home offices rely on LB-Link routers for internet connectivity. A compromised router could lead to interception and manipulation of sensitive data, unauthorized access to internal networks, and disruption of business operations. Given the routers' role as network gateways, attackers could establish persistent footholds, conduct man-in-the-middle attacks, or launch further attacks against corporate resources. The impact extends to confidentiality, integrity, and availability of network communications. Additionally, critical infrastructure or public sector organizations using these devices could face operational disruptions or data breaches. The absence of authentication in the vulnerable interface increases the likelihood of automated exploitation attempts, raising the risk of widespread attacks if patches or mitigations are not promptly applied.

To mitigate this vulnerability, affected organizations should immediately identify if they are using any of the vulnerable LB-Link router models and firmware versions. Since no official patches or updates are currently linked, organizations should: 1) Restrict access to the router's management interfaces by limiting them to trusted internal networks and disabling remote management where possible. 2) Implement network segmentation to isolate vulnerable devices from critical systems. 3) Monitor network traffic for unusual activity indicative of exploitation attempts, such as unexpected commands or configuration changes. 4) Consider replacing vulnerable devices with routers from vendors that provide timely security updates and have robust security features. 5) Regularly check LB-Link’s official channels for firmware updates addressing this vulnerability and apply them promptly once available. 6) Employ intrusion detection/prevention systems (IDS/IPS) that can detect command injection patterns or anomalous HTTP requests targeting the /goform/set_serial_cfg endpoint. 7) Educate users and administrators about the risks of unauthorized access and the importance of securing network devices.