CVE-2025-5228 is a critical stack-based buffer overflow vulnerability identified in the D-Link DI-8100 router, specifically affecting the httpd_get_parm function within the /login.cgi component of the embedded jhttpd web server. The vulnerability arises from improper handling of the 'notify' parameter, which can be manipulated to overflow a stack buffer. This overflow can potentially allow an attacker to execute arbitrary code or cause a denial of service by crashing the device. The vulnerability is exploitable without authentication and does not require user interaction, but the attack vector is limited to the local network (AV:A), meaning an attacker must have network access to the device's LAN segment. The CVSS 4.0 base score is 8.7 (high severity), reflecting the high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges or user interaction required. Although no public exploits are currently known in the wild, the vulnerability has been publicly disclosed, increasing the risk of exploitation. The affected version is firmware up to 20250523, and no official patches or mitigations have been linked yet. This vulnerability poses a significant risk to devices running this firmware, potentially allowing attackers to gain control over the router, intercept or manipulate network traffic, or disrupt network services.

For European organizations, this vulnerability presents a substantial risk, especially for those relying on the D-Link DI-8100 router in their local networks. Successful exploitation could lead to full compromise of the affected router, enabling attackers to intercept sensitive communications, redirect traffic, or establish persistent footholds within internal networks. This could result in data breaches, espionage, or disruption of critical network services. Given the router's role as a gateway device, compromise could also facilitate lateral movement to other internal systems. The local network attack vector limits remote exploitation but does not eliminate risk, as attackers could gain local access through compromised devices, insider threats, or physical proximity. Organizations with less mature network segmentation or those employing these routers in sensitive environments are particularly vulnerable. The absence of a patch increases exposure time, and the public disclosure may accelerate exploit development. Thus, the vulnerability could have severe operational and reputational impacts on European enterprises, especially those in sectors such as finance, government, healthcare, and critical infrastructure.

European organizations should immediately identify any D-Link DI-8100 devices running firmware up to version 20250523 within their networks. Network segmentation should be enforced to restrict access to router management interfaces strictly to authorized personnel and systems. Implementing network access controls such as VLANs, firewall rules, and NAC (Network Access Control) can limit exposure to local network attacks. Monitoring network traffic for unusual activity targeting the /login.cgi endpoint or anomalous HTTP requests can help detect exploitation attempts. Organizations should also consider disabling remote management features if enabled and changing default credentials to strong, unique passwords. Until an official patch is released, deploying compensating controls such as isolating vulnerable devices on dedicated management VLANs or physically restricting access may reduce risk. Additionally, organizations should stay informed about vendor advisories for patches or firmware updates and plan prompt deployment once available. Conducting internal penetration testing and vulnerability assessments focusing on router security can further identify and mitigate risks.