CVE-2000-0262 is a vulnerability found in the AVM KEN! ISDN Proxy server versions 1.3.10 and 1.4.30. This vulnerability allows remote attackers to cause a denial of service (DoS) condition by sending a malformed request to the server. The AVM KEN! ISDN Proxy server is used to manage ISDN connections, typically in telecommunication and networking environments. The flaw does not impact confidentiality or integrity but affects availability by crashing or otherwise disrupting the service. The vulnerability requires no authentication and can be exploited remotely over the network, making it relatively easy to trigger. However, the lack of a patch and the age of the vulnerability (published in April 2000) suggest that modern systems may no longer use these versions or the product itself. There are no known exploits in the wild, and no detailed technical information about the malformed request is provided. The CVSS score of 5.0 (medium severity) reflects the limited impact scope—only availability is affected, and no user interaction is required. Since the vulnerability affects a niche product related to ISDN proxying, its exploitation potential is limited to environments still running these legacy versions.

For European organizations, the impact of this vulnerability largely depends on whether they still operate legacy telecommunication infrastructure using the AVM KEN! ISDN Proxy server versions 1.3.10 or 1.4.30. In sectors where ISDN lines are still in use, such as certain government agencies, telecommunications providers, or industrial environments, an attacker could remotely disrupt ISDN proxy services, leading to denial of service conditions. This could interrupt critical communication channels, affecting operational continuity. However, given the age of the vulnerability and the general migration away from ISDN technology towards IP-based communications, the practical impact today is likely limited. Organizations relying on legacy ISDN infrastructure should be aware of this risk, as denial of service could degrade network availability and potentially impact dependent services. The vulnerability does not allow data theft or modification, so confidentiality and integrity impacts are negligible.

Since no patch is available for this vulnerability, organizations should consider the following specific mitigation steps: 1) Identify and inventory all instances of AVM KEN! ISDN Proxy servers in their environment, focusing on versions 1.3.10 and 1.4.30. 2) Where possible, upgrade to newer versions or replace the ISDN proxy infrastructure with modern, supported solutions that do not have this vulnerability. 3) Implement network-level protections such as firewalls or intrusion prevention systems (IPS) to restrict access to the ISDN proxy server from untrusted networks, limiting exposure to potential attackers. 4) Monitor network traffic for malformed requests or unusual activity targeting the ISDN proxy server to detect potential exploitation attempts. 5) If replacement or upgrade is not immediately feasible, consider isolating the vulnerable servers within segmented network zones to reduce attack surface. 6) Develop incident response plans specifically addressing denial of service scenarios affecting telecommunication proxies to minimize operational disruption.