CVE-2025-13562 is a remotely exploitable command injection vulnerability found in the D-Link DIR-852 router firmware version 1.00. The vulnerability stems from improper sanitization or validation of the 'service' parameter in the /gena.cgi CGI script, which processes incoming requests. An attacker can craft a malicious request to this endpoint, injecting arbitrary shell commands that the router executes with system-level privileges. This allows full control over the device, potentially enabling attackers to manipulate network traffic, deploy malware, or pivot to internal networks. The vulnerability requires no authentication or user interaction, making it highly accessible to remote attackers. However, the impact is somewhat limited by the router’s role and network placement. The product is no longer supported by D-Link, meaning no official patches or firmware updates are available to remediate the issue. The CVSS 4.0 score of 6.9 reflects a medium severity rating, considering the ease of exploitation and moderate impact on confidentiality, integrity, and availability. Although no active exploitation has been reported, the public availability of exploit code increases the risk of opportunistic attacks. The vulnerability primarily affects home and small office environments where this router model is deployed, but compromised devices could serve as entry points into larger organizational networks if not properly segmented.

For European organizations, the primary impact of this vulnerability lies in the potential compromise of network perimeter devices that use the D-Link DIR-852 router. Attackers gaining control over these routers can intercept or redirect network traffic, launch further attacks against internal systems, or use the device as a foothold for lateral movement. This can lead to data breaches, disruption of network services, and loss of confidentiality and integrity of communications. Small and medium enterprises (SMEs) and home office setups, which often rely on consumer-grade routers like the DIR-852, are particularly at risk. The lack of vendor support and patches means that vulnerable devices will remain exposed unless proactively replaced or mitigated. Additionally, compromised routers can be conscripted into botnets or used for distributed denial-of-service (DDoS) attacks, affecting broader network stability. The medium severity rating suggests that while the threat is serious, it may not result in catastrophic organizational impact unless combined with other vulnerabilities or poor network hygiene.

Given the absence of official patches, European organizations should prioritize replacing the affected D-Link DIR-852 routers with supported and updated models. Network administrators should immediately disable remote management interfaces and restrict access to router management ports to trusted internal networks only. Implement network segmentation to isolate vulnerable devices from critical infrastructure and sensitive data environments. Employ intrusion detection and prevention systems (IDS/IPS) to monitor for suspicious traffic targeting the /gena.cgi endpoint or unusual command execution patterns. Regularly audit network devices for outdated firmware and unsupported hardware to proactively identify and remediate risks. Educate users about the risks of using end-of-life network equipment and encourage timely hardware upgrades. If replacement is not immediately feasible, consider deploying firewall rules to block incoming traffic to the vulnerable CGI endpoint and limit exposure to untrusted networks. Maintain up-to-date network monitoring and incident response plans to quickly detect and respond to potential exploitation attempts.