CVE-2025-29523 is a command injection vulnerability identified in the D-Link DSL-7740C router running firmware version DSL7740C.V6.TR069.20211230. The vulnerability exists in the implementation of the ping6 function, which is typically used to send ICMPv6 echo requests for network diagnostics. Due to improper input validation or sanitization, an attacker can inject arbitrary commands through the ping6 interface. This flaw allows an attacker with access to the vulnerable device's interface to execute arbitrary system commands with the privileges of the affected service, potentially leading to full system compromise. The vulnerability does not specify affected firmware versions beyond the one mentioned, and no patches or known exploits in the wild have been reported as of the publication date. The absence of a CVSS score indicates that the vulnerability is newly disclosed and has not yet been fully assessed for severity. However, command injection vulnerabilities are generally critical due to their potential to allow remote code execution. The attack vector likely requires network access to the device's management interface or the ability to send crafted ping6 requests, which may be limited to local network access or authenticated users depending on device configuration. The vulnerability's exploitation could lead to unauthorized control over the router, enabling attackers to intercept or manipulate network traffic, disrupt service availability, or pivot into internal networks.

For European organizations, this vulnerability poses a significant risk, especially for those using the D-Link DSL-7740C routers in their network infrastructure. Compromise of these routers could lead to interception of sensitive data, disruption of internet connectivity, and unauthorized access to internal networks. Given the critical role of routers in network security and traffic management, exploitation could facilitate advanced persistent threats, data breaches, or denial of service conditions. Organizations in sectors such as telecommunications, finance, government, and critical infrastructure are particularly at risk due to the potential for operational disruption and data exfiltration. The impact is heightened if the devices are deployed in environments with limited network segmentation or weak access controls. Additionally, the use of IPv6 and the ping6 function suggests that networks with IPv6 enabled are more susceptible. Since no known exploits are currently in the wild, proactive mitigation is crucial to prevent future attacks.

Organizations should immediately identify and inventory all D-Link DSL-7740C devices running the vulnerable firmware version. Network administrators should restrict access to router management interfaces, especially limiting IPv6 ICMP traffic such as ping6 requests to trusted sources only. Implement network segmentation to isolate critical infrastructure and management interfaces from general user networks. Monitor network traffic for unusual ping6 activity or command injection attempts. Since no official patch is currently available, consider temporary mitigations such as disabling IPv6 on affected devices if feasible or applying firewall rules to block malicious input vectors. Engage with D-Link support or security advisories for updates or patches addressing this vulnerability. Additionally, implement strong authentication mechanisms and regularly update device firmware to the latest versions once patches are released. Conduct penetration testing and vulnerability assessments to verify the effectiveness of mitigations.