CVE-2000-0152 is a medium-severity vulnerability affecting Novell BorderManager versions 3.0 and 3.5. The vulnerability allows remote attackers to cause a denial of service (DoS) condition by simply pressing the enter key during a Telnet session connected to port 2000. This behavior suggests that the BorderManager service listening on port 2000 does not properly handle unexpected or malformed input, leading to a crash or service disruption. Since the attack requires no authentication and can be triggered remotely, it poses a risk to the availability of the BorderManager service. The vulnerability does not impact confidentiality or integrity, as it only causes service interruption. No patches are available for this issue, and there are no known exploits in the wild, indicating limited active exploitation. However, the ease of triggering the DoS by a simple keystroke makes it a straightforward attack vector for disrupting network security infrastructure relying on BorderManager. Given the age of the product and vulnerability (published in 2000), this issue primarily affects legacy systems still running these versions of Novell BorderManager.

For European organizations using Novell BorderManager 3.0 or 3.5, this vulnerability could lead to temporary denial of service of critical network security functions such as firewalling, VPN, or proxy services managed by BorderManager. Disruption of these services can impact business continuity, especially for organizations relying on BorderManager for perimeter security or remote access. Although the vulnerability does not allow data breaches or privilege escalation, the loss of availability can degrade security posture and operational capabilities. In sectors like finance, government, or critical infrastructure within Europe, even short service outages can have regulatory and operational consequences. The lack of a patch means organizations must rely on compensating controls or migration to newer, supported solutions to mitigate risk.

Since no official patch is available, European organizations should consider the following specific mitigations: 1) Restrict access to port 2000 on BorderManager servers using network-level controls such as firewalls or access control lists (ACLs) to limit Telnet connections only to trusted management hosts. 2) Disable or remove Telnet services on port 2000 if not strictly required, or replace Telnet with more secure management protocols like SSH. 3) Monitor network traffic to detect unusual or repeated Telnet connection attempts to port 2000, which could indicate exploitation attempts. 4) Plan and execute migration from Novell BorderManager 3.x to a modern, supported security gateway solution that addresses this and other legacy vulnerabilities. 5) Implement network segmentation to isolate BorderManager servers from general user networks, reducing exposure. 6) Employ intrusion detection/prevention systems (IDS/IPS) with custom rules to detect and block malformed Telnet input targeting port 2000.