CVE-2025-55611 is a critical buffer overflow vulnerability identified in the D-Link DIR-619L router firmware version 2.06B01. The vulnerability exists in the formLanguageChange function, which improperly handles the nextPage parameter. Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, potentially overwriting adjacent memory. In this case, the nextPage parameter is not properly validated or sanitized, allowing an attacker to craft a malicious request that overflows the buffer. This can lead to arbitrary code execution, denial of service, or complete compromise of the affected device. The vulnerability has a CVSS v3.1 base score of 9.8, indicating critical severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and impacts confidentiality, integrity, and availability (C:H/I:H/A:H). The vulnerability is exploitable remotely without authentication, making it highly dangerous. Although no known exploits are currently reported in the wild, the nature of the vulnerability and the critical CVSS score suggest that exploitation could allow attackers to take full control of the router, intercept or manipulate network traffic, or disrupt network services. The vulnerability is classified under CWE-120 (Classic Buffer Overflow), a well-known and widely exploited category of software flaws. No patches or fixes have been linked yet, indicating that affected users should consider mitigation strategies until an official update is released.

For European organizations, the impact of this vulnerability can be significant. The D-Link DIR-619L is a consumer and small office/home office (SOHO) router model that may be deployed in various environments including small businesses, remote offices, and home networks of employees. Successful exploitation could allow attackers to gain persistent access to internal networks, intercept sensitive communications, or launch further attacks against corporate infrastructure. This is particularly concerning for organizations with remote or hybrid work models relying on such routers for connectivity. Confidentiality is at risk due to potential data interception; integrity is compromised by possible manipulation of network traffic; and availability can be disrupted by denial of service or device takeover. Additionally, compromised routers can be leveraged as entry points for lateral movement or as part of botnets for broader attacks. The lack of authentication and user interaction requirements lowers the barrier for exploitation, increasing the threat level. Given the criticality and ease of exploitation, European organizations using this router model should prioritize detection and mitigation to prevent potential breaches and operational disruptions.

1. Immediate Network Segmentation: Isolate affected D-Link DIR-619L routers from critical network segments to limit potential lateral movement if compromised. 2. Disable Remote Management: If remote management features are enabled on these routers, disable them to reduce exposure to external attackers. 3. Monitor Network Traffic: Deploy network monitoring tools to detect unusual traffic patterns or attempts to exploit the nextPage parameter in HTTP requests targeting the router's management interface. 4. Apply Vendor Patches: Continuously monitor D-Link's official channels for firmware updates addressing this vulnerability and apply them promptly once available. 5. Replace or Upgrade Hardware: For environments where patching is delayed or unavailable, consider replacing the DIR-619L routers with models not affected by this vulnerability or from vendors with timely security support. 6. Implement Intrusion Prevention Systems (IPS): Configure IPS signatures to detect and block exploitation attempts targeting buffer overflow patterns in router management interfaces. 7. Educate Users: Inform employees and IT staff about the risks associated with vulnerable routers and encourage reporting of unusual device behavior. 8. Conduct Regular Vulnerability Scans: Include network devices in vulnerability assessments to identify and remediate outdated or vulnerable firmware versions proactively.