CVE-2025-11099 is a command injection vulnerability identified in the D-Link DIR-823X router, specifically in version 250416. The vulnerability resides in the function uci_del within the /goform/delete_prohibiting endpoint. This function improperly handles the argument 'delvalue', allowing an attacker to inject arbitrary commands. Since the vulnerability can be exploited remotely without user interaction or authentication, an attacker can execute arbitrary commands on the device with limited privileges. The vulnerability is rated with a CVSS 4.0 score of 5.3 (medium severity), reflecting a network attack vector with low complexity and no required privileges or user interaction, but limited impact on confidentiality, integrity, and availability. The vulnerability does not require prior authentication, making it accessible to unauthenticated remote attackers. Although no known exploits are currently observed in the wild, the public disclosure increases the risk of exploitation. The vulnerability affects a widely deployed consumer and small office router model, which is often used as a gateway device, making it a potential entry point for attackers to pivot into internal networks. The lack of available patches or mitigations from the vendor at this time further increases exposure. Attackers exploiting this vulnerability could execute arbitrary commands on the router, potentially leading to device compromise, network traffic interception, or further lateral movement within the network.

For European organizations, the impact of this vulnerability could be significant, especially for small and medium enterprises (SMEs) and home office environments that rely on the D-Link DIR-823X router for internet connectivity. Successful exploitation could allow attackers to gain control over the router, enabling interception or manipulation of network traffic, disruption of internet access, or use of the device as a foothold for launching further attacks against internal systems. This could lead to data breaches, loss of confidentiality, and operational disruption. Given the router's role as a network gateway, compromise could undermine perimeter defenses and expose sensitive internal resources. Additionally, the vulnerability's remote exploitability without authentication increases the risk of widespread scanning and exploitation campaigns targeting vulnerable devices across Europe. Organizations with limited IT security resources may be particularly vulnerable due to delayed patching or lack of awareness. The medium severity rating suggests that while the impact is not critical, the potential for network compromise and data exposure warrants prompt attention.

1. Immediate mitigation should include isolating affected D-Link DIR-823X devices from critical internal networks to limit potential lateral movement. 2. Network administrators should monitor network traffic for unusual activity originating from or targeting these routers, including unexpected command execution patterns or outbound connections. 3. Implement network segmentation to restrict access to router management interfaces from untrusted networks. 4. Disable remote management features on the router if not required, to reduce the attack surface. 5. Regularly check for vendor advisories and apply firmware updates as soon as patches become available. 6. Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting command injection attempts targeting the /goform/delete_prohibiting endpoint. 7. For organizations using these devices, consider replacing vulnerable routers with models that have confirmed security updates or better security track records. 8. Educate users and IT staff about the risks of using outdated router firmware and the importance of timely updates. 9. Use network access control (NAC) to enforce device compliance and prevent vulnerable devices from connecting to sensitive network segments.