CVE-2026-1125 is a remote command injection vulnerability identified in the D-Link DIR-823X router, firmware version 250416. The vulnerability exists in the function sub_412E7C within the /goform/set_wifidog_settings endpoint, where the wd_enable parameter is not properly sanitized. This improper input validation allows an attacker to inject arbitrary OS commands that the router executes with elevated privileges. The attack vector is network-based and requires no authentication or user interaction, making it highly accessible to remote attackers. The vulnerability's CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P) indicates that exploitation is possible over the network with low complexity and no privileges or user interaction required, but with limited impact on confidentiality, integrity, and availability. The exploit code has been publicly disclosed, increasing the likelihood of exploitation attempts. While no active exploitation has been reported, the presence of a public exploit and the critical nature of router devices as network gateways make this vulnerability significant. Attackers exploiting this flaw could execute arbitrary commands, potentially leading to full device compromise, interception or manipulation of network traffic, and pivoting to internal networks.

For European organizations, exploitation of CVE-2026-1125 could lead to severe network security breaches. Compromised routers can serve as entry points for attackers to intercept sensitive communications, deploy malware, or launch further attacks within corporate or governmental networks. The integrity and availability of network services could be disrupted, impacting business operations and critical infrastructure. Given the widespread use of D-Link routers in small to medium enterprises and some public sector deployments across Europe, the vulnerability poses a tangible risk. Additionally, the ability to remotely execute commands without authentication increases the threat level, especially in environments with limited network segmentation or outdated firmware management practices. The exposure is particularly critical for organizations handling sensitive data or those involved in critical infrastructure sectors such as energy, transportation, and telecommunications.

Organizations should immediately verify if they use the D-Link DIR-823X router with firmware version 250416 and prioritize upgrading to a patched firmware version once available from D-Link. In the absence of an official patch, network administrators should restrict access to the router's management interfaces by implementing strict firewall rules to block external access to the /goform/set_wifidog_settings endpoint. Disabling remote management features and isolating the router management network segment can reduce exposure. Monitoring network traffic for unusual commands or connections to the vulnerable endpoint is advised. Employing network intrusion detection systems (NIDS) with signatures for known exploits targeting this vulnerability can provide early warning. Regularly auditing router configurations and applying security best practices such as changing default credentials and using strong passwords will further mitigate risk. Finally, organizations should maintain an incident response plan to quickly address any signs of compromise related to this vulnerability.