CVE-2025-44835 is a command injection vulnerability identified in the D-Link DIR-816 A2V1.1.0B05 router firmware. The flaw exists in the iptablesWebsFilterRun function, which is responsible for managing firewall rules via the device's web interface. Due to insufficient input validation, remote attackers with low privileges can inject arbitrary shell commands through crafted inputs to this function. This vulnerability falls under CWE-77 (Improper Neutralization of Special Elements used in a Command), indicating that user-supplied data is not properly sanitized before being passed to a system shell. Exploitation does not require user interaction but does require some level of authentication (PR:L), suggesting that attackers must have access to the device's management interface, either through default or compromised credentials or via network access. Successful exploitation can lead to arbitrary command execution on the router, potentially allowing attackers to manipulate firewall rules, intercept or redirect traffic, or pivot into the internal network. The CVSS 3.1 base score is 6.3 (medium severity), reflecting the network attack vector (AV:N), low attack complexity (AC:L), required privileges (PR:L), no user interaction (UI:N), and impacts on confidentiality, integrity, and availability rated as low (C:L/I:L/A:L). No known exploits are currently reported in the wild, and no patches have been published as of the vulnerability disclosure date (May 1, 2025).

For European organizations, this vulnerability poses a moderate risk primarily to those using the D-Link DIR-816 router model with the affected firmware version. Successful exploitation could allow attackers to execute arbitrary commands on the router, potentially leading to unauthorized changes in firewall configurations, interception or redirection of network traffic, and compromise of internal network segments. This could result in data leakage, disruption of network services, or facilitate further attacks such as lateral movement or deployment of malware. Small and medium enterprises (SMEs) and home office environments that rely on this router model for perimeter security are particularly vulnerable. Given that the attack requires authentication, risks increase if default or weak credentials are in use or if attackers gain access through other means such as phishing or network intrusion. The absence of patches and known exploits suggests a window of exposure, emphasizing the need for proactive mitigation. Critical infrastructure and organizations with high-value data in sectors like finance, healthcare, and government could face elevated risks if these routers are deployed within their network perimeters.

Immediately audit all D-Link DIR-816 routers in use to identify firmware versions and confirm if they match the vulnerable version A2V1.1.0B05. Change all default or weak administrative credentials on affected devices to strong, unique passwords to reduce the risk of unauthorized access. Restrict access to the router management interface by limiting it to trusted IP addresses or disabling remote management where possible. Implement network segmentation to isolate vulnerable routers from critical internal systems, minimizing potential lateral movement. Monitor network traffic and router logs for unusual activity indicative of command injection attempts or unauthorized configuration changes. Apply any firmware updates or patches released by D-Link promptly once available; if no official patch is provided, consider replacing affected devices with models not impacted by this vulnerability. Educate network administrators and users on the risks of credential compromise and enforce multi-factor authentication (MFA) for device management interfaces if supported. Deploy intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting command injection attempts targeting router management interfaces.