CVE-2000-0140 is a vulnerability in the Internet Anywhere POP3 Mail Server version 3.1.3 that allows remote attackers to cause a denial of service (DoS) condition. The issue arises because the server does not properly handle a large number of simultaneous connections, which can exhaust server resources and render the mail service unavailable to legitimate users. This vulnerability requires no authentication and can be exploited remotely over the network. The attack vector involves flooding the POP3 server with numerous connection attempts, overwhelming its capacity to manage sessions and leading to service disruption. Since the vulnerability affects availability only, it does not compromise confidentiality or integrity of the mail data. No patch is available for this vulnerability, and there are no known exploits actively observed in the wild. The CVSS v2 base score is 5.0, indicating a medium severity level, with the vector AV:N/AC:L/Au:N/C:N/I:N/A:P, meaning network attack vector, low attack complexity, no authentication required, and impact limited to availability.

For European organizations using Internet Anywhere POP3 Mail Server version 3.1.3, this vulnerability poses a risk of service disruption through denial of service attacks. Disruption of mail services can affect business communications, delay critical information exchange, and reduce operational efficiency. Although the vulnerability does not allow data theft or modification, the unavailability of email services can impact customer service, internal coordination, and compliance with communication regulations such as GDPR if timely responses are hindered. Organizations relying on legacy mail infrastructure or lacking modern email platforms may be more vulnerable. The lack of a patch means organizations must rely on alternative mitigations to maintain service availability. Given the age of the vulnerability (published in 2000), it is less likely to affect organizations that have upgraded or migrated to newer mail servers, but legacy systems in use in certain sectors or smaller enterprises may still be at risk.

Since no patch is available, European organizations should consider the following specific mitigations: 1) Implement network-level rate limiting and connection throttling on firewalls or intrusion prevention systems to restrict the number of simultaneous connections to the POP3 server from a single IP or subnet. 2) Deploy access control lists (ACLs) to restrict POP3 server access only to trusted IP addresses or internal networks where possible. 3) Monitor network traffic for unusual spikes in POP3 connection attempts and configure alerts for potential DoS activity. 4) Consider migrating from Internet Anywhere POP3 Mail Server 3.1.3 to a modern, actively maintained mail server solution that includes built-in protections against DoS attacks. 5) Use email gateway appliances or cloud-based email services that provide DoS protection and redundancy. 6) If migration is not immediately feasible, isolate the vulnerable server behind a reverse proxy or load balancer that can absorb or filter excessive connection attempts. These measures will help reduce the risk of service disruption while maintaining operational continuity.