CVE-2025-11338 is a buffer overflow vulnerability identified in the D-Link DI-7100G C1 device, specifically within the jhttpd web server component's /webchat/login.cgi script. The vulnerability exists in the function sub_4C0990, which processes the 'openid' argument. Improper bounds checking or input validation allows an attacker to craft a malicious request that overflows the buffer, potentially overwriting memory and enabling arbitrary code execution. The vulnerability is remotely exploitable without requiring authentication or user interaction, making it particularly dangerous. The CVSS 4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. Although no known exploits have been observed in the wild, a public exploit has been published, increasing the likelihood of exploitation attempts. The affected firmware version is up to 20250928, and no official patch links are currently available, indicating that vendors and users must remain vigilant. The vulnerability could be leveraged to take control of the device, disrupt network operations, or pivot into internal networks, especially in environments where these devices serve critical roles.

For European organizations, the impact of CVE-2025-11338 is significant due to the potential for full device compromise. The D-Link DI-7100G C1 is often deployed in enterprise and telecommunications environments, where device integrity is critical. Exploitation could lead to unauthorized access to internal networks, interception or manipulation of sensitive communications, and disruption of network services. This can affect confidentiality by exposing sensitive data, integrity by allowing malicious modifications, and availability by causing device crashes or denial of service. Given the remote and unauthenticated nature of the exploit, attackers can target these devices at scale, increasing the risk of widespread disruption. Organizations involved in critical infrastructure, government, or large-scale enterprise networks in Europe could face operational and reputational damage. The lack of an official patch at the time of disclosure further exacerbates the risk, necessitating interim protective measures.

1. Immediate network-level mitigation: Block or restrict access to the /webchat/login.cgi endpoint on the DI-7100G C1 devices using firewalls or intrusion prevention systems to prevent exploitation attempts. 2. Network segmentation: Isolate vulnerable devices from critical internal networks to limit potential lateral movement if compromised. 3. Monitor network traffic for anomalous requests targeting the 'openid' parameter or unusual HTTP POST requests to the vulnerable CGI script. 4. Deploy host-based intrusion detection systems (HIDS) on networks hosting these devices to detect exploitation attempts. 5. Engage with D-Link support channels to obtain firmware updates or patches as soon as they become available and apply them promptly. 6. If patching is delayed, consider temporary device replacement or disabling vulnerable services where feasible. 7. Conduct regular vulnerability scans and penetration tests to identify the presence of vulnerable devices and verify mitigation effectiveness. 8. Educate network administrators about this vulnerability and ensure incident response plans include procedures for this specific threat.